This is a case of second impression. In North Carolina Utilities Commission v. FCC, 537 F.2d 787 (4th Cir. 1976), petition for cert. denied, - U.S. -, 97 S.Ct. 651, 50 L.Ed.2d 631, (1976), this Court upheld a declaratory ruling of the Federal Communications Commission that the Communications Act of 1934 preempts state regulation of telephone terminal equipment used for both interstate and local communication when such regulation conflicts with federal rules governing the same equipment. This appeal concerns the validity of the FCC’s attempt to exercise that primary authority.
I. THE TERMINAL EQUIPMENT REGISTRATION PROGRAM
The phrase “terminal equipment” refers to devices utilized for transmission or reception of communications when attached to the national telecommunication line network. Items of terminal equipment include common residential telephones (both main station and extension phones), key telephones, answering devices, dialers, computer terminals and private branch exchanges (PBX’s). Although most telephone customers rent or purchase terminal equipment directly from telephone companies, the carriers themselves purchase a substantial por*1041tion of their terminal equipment from independent manufacturers as well as carrier-controlled subsidiaries.
In Docket 19528, the present case, the Federal Communications Commission (FCC). has by rule established a registration program for all terminal equipment attached to the interstate telephone line network. Attachment of terminal equipment is currently restricted by telephone company tariffs which allow customer connection of non-carrier-supplied terminal equipment to the telephone lines only if the customer effects connection through a carrier-supplied connecting arrangement (CA) and employs a carrier-supplied network control signaling unit (NCSU). The proposed FCC program would permit customers to attach any registered terminal equipment to the network without being forced to use the carrier-supplied intermediary devices.
To be registered with the FCC, equipment must meet technical specifications that ensure proper performance and safety without the intermediary CAs and NCSUs. Nonregistered equipment can still be attached provided the intermediary devices are employed. All terminal equipment, including that provided by carriers directly to customers, must be registered (or attached using CAs and NCSUs). Individual items of terminal equipment, however, need not be registered; instead, manufacturers will be required to register types or models of equipment.
II. THE CONDITIONS OF CONTEST
A. The Statutory Scheme. — The Communications Act of 1934, 47 U.S.C.A. §§ 151-609 (1962 & Supp. 1976), created the Federal Communications Commission for “the purpose of regulating interstate and foreign commerce in communications by wire and radio so as to make available a rapid, efficient, Nationwide, and world-wide wire and radio communication service with adequate facilities at reasonable charges,” Communications Act § 1, 47 U.S.C.A. § 151. Section 2(a) of the Act, 47 U.S.C.A. § 152(a), provides that the Act and the FCC’s jurisdiction “shall apply to all interstate and foreign communication by wire.” This general grant of authority to the FCC is amplified by section 3(a), 47 U.S.C.A. § 153(a), to encompass “the transmission of writing, signs, signals, pictures, and sounds of all kinds by aid of wire . including all instrumentalities, facilities, apparatus, and services incidental to such transmission..” (Emphasis added.)
The Commission’s major substantive powers over common carriers are described by sections 201 — 205 of the Act, 47 U.S.C.A. §§ 201-205. Section 201(b) requires that all “charges, practices, classifications, and regulations for and in connection with [interstate] communication service, shall be just and reasonable.” Section 202(a) declares it to be “unlawful for any common carrier to make any unjust or unreasonable discrimination in charges, practices, classifications, regulations, facilities, or services” of interstate communication. Section 203 and 204 mandate procedures for tariff filings by carriers and for FCC review of proposed tariffs. Although the FCC may simply disapprove a proposed tariff provision and require refiling by a carrier, section 205 also gives the FCC power to “prescribe what will be the just and reasonable charge and what classification, regulation, or practice is or will be just, fair, and reasonable, to be thereafter followed” by the carrier.
The Communications Act also reserves some regulatory jurisdiction to the states. Section 2(b)(1) of the Act, 47 U.S.C.A. § 152(b)(1), provides that “nothing” in the Act shall be construed to give the Commission jurisdiction “with respect to . charges, classifications, practices, services, facilities or regulations for or in connection with intrastate communication service.” (Emphasis added.) Section 221(b) of the Act, 47 U.S.C.A. § 221(b), carves out a second area of state regulatory hegemony by denying the Commission jurisdiction with respect to “charges, classifications, practices, services, facilities or regulations for or in connection with . . . telephone exchange service” where “such matters are subject to regulation by a State *1042commission or by local governmental authority” even though “a portion of such exchange service constitutes interstate or foreign communication.”
The tension between the powers granted to the FCC by sections 2(a) and 3(a), and the powers reserved to the states by sections 2(b)(1) and 221(b), generates this particular appeal. The validity of the Commission’s registration program, however, cannot be properly determined without reference to the development of the Commission’s interconnection policy.
B. The Interconnection Policy and North Carolina I. — Prior to 1969, AT&T tariffs filed with the Commission prohibited attachment of any non-carrier-supplied terminal equipment to the telephone line network.1 Earlier in 1966, manufacturers of the Carterphone device, which enabled a radio transmitter to interconnect with the telephone network, had attacked the tariff as an antitrust violation, but the courts held that the FCC had primary jurisdiction to determine the lawfulness of the inclusion of the blanket prohibition in an FCC-approved tariff. Carter v. AT&T Co., 250 F.Supp. 188, 190 (N.D.Tex.), aff’d 365 F.2d 486 (5th Cir. 1966), cert. denied 385 U.S. 1008, 87 S.Ct. 714, 17 L.Ed.2d 546 (1967). The FCC then found that the absolute prohibition of customer interconnection was unreasonable and unjustly discriminatory in violation of sections 201 and 202 of the Act. Carterphone v. AT&T, 13 F.C.C.2d 420 (1968), reconsideration denied, 14 F.C.C.2d 571.2 The Commission did not, however, affirmatively prescribe any specific interconnection policy for the carriers, as it might have done pursuant to section 205. Rather, it declared the AT&T tariff to be invalid, and permitted the carriers to refile. 13 F.C.C.2d at 425.3 The carriers responded by filing tariffs that contained the current CA and NCSU requirements. The Commission did not object to the refiled tariffs, and permitted them to become effective without scheduling a formal investigation, see AT&T “Foreign Attachment” Tariff Revisions, 15 F.C.C.2d 605 (1968), 18 F.C.C.2d 871 (1969), although the FCC still retained authority to investigate the lawfulness of the tariffs in the future, see 47 U.S.C.A. § 403.4
*1043Despite this federal tariff permitting interconnection of terminal equipment (as long as CAs and NCSUs were used), several state regulatory commissions in the early 1970’s planned to forbid interconnection of non-carrier-supplied terminal equipment with local exchanges, except where such equipment was used exclusively for interstate communication. Because separation of terminal equipment used exclusively for local communication is a practical and economic impossibility, the proposed state rules would have scuttled the federal interconnection policy. Acting on the petition of independent equipment manufacturers, the FCC ruled that state commissions were precluded from regulating or restricting interconnection in any fashion that conflicted with FCC regulations governing the same equipment. In the Matter of Telerent Leasing Corp., 45 F.C.C.2d 204 (1974).
On appeal to this Court, the FCC’s action was affirmed. North Carolina Utilities Commission v. FCC, 537 F.2d 787 (4th Cir. 1976) (North Carolina I), petition for cert. denied, - U.S. -, 97 S.Ct. 651, 50 L.Ed.2d 631 (1976). The Court first noted the impossibility of separating interstate terminal equipment from local terminal equipment: the same telephones are used for both interstate and local communications. Thus, if state commissions could lawfully prohibit interconnection unless terminal equipment is used exclusively for interstate communications, federal tariffs authorizing interconnection would be made nugatory. Conversely, if federal regulations permitting interconnection are primary, it becomes a practical impossibility for the states to prohibit interconnection with respect to purely intrastate communication. Something had to give.
This Court held that FCC authority to regulate interconnection of equipment used for both interstate and local communication was paramount. Considerations of congressional purpose, of statutory provision for parallel situations, and of established agency practice informed the Court’s decision. First, the Court pointed out that the Communications Act’s primary purpose of establishing an efficient interstate communications network “with adequate facilities at reasonable charges,” see 47 U.S.C.A. § 151, would be jeopardized if federal regulation of jointly used equipment could be countermanded by state rules. Second, the Court found that other provisions of the Communications Act establish federal primacy where the control of facilities used for both interstate and local communication is concerned. Sections 2(b)(2) through 2(b)(4), for example, make intrastate carriers subject to FCC regulation when they provide interstate service by hooking up with the lines of interstate carriers, see 4H U.S.C.A. § 152(b)(2)-(4); and section 410(c) establishes federal preeminence in the allocation of rate base between interstate and local services, see 47 U.S.C.A. § 410(c) (Supp.1976). Finally, invoking the principle that an agency’s established construction of its enabling legislation is entitled to deference,5 the Court noted that the FCC has consistently asserted its jurisdiction over facilities and equipment used in both interstate and local communication.
C. The Present Challenge. — The genesis of this dispute was the Commission’s determination, shortly after its 1969 Carterphone decision, to study the technical justifications for the carrier-promulgated connecting arrangement tariffs. This investigation was formalized in Docket 19528 for the announced purpose of ascertaining the best technical method of effecting the interconnection policy. In its Notice of Inquiry, the FCC attempted to insulate Docket 19528 from any further dispute about the wisdom of interconnection as a policy goal by stating that “it is not our intention to consider . any question as to whether there should be any modification of our holding in Carterphone or any revisions in the tariff provisions applicable to” customer intercon*1044nection, 35 F.C.C.2d 539, 542 (1972). The Commission did, however, begin a separate proceeding — Docket 20003 — to consider, inter alia, the long-term economic impact of liberalized interconnection, and expressed a willingness to consider evidence contrary to the public policy judgment adumbrated by Carterphone. Customer Interconnection, 46 F.C.C.2d 214, 216-218 (1974). A First Report in Docket 20003 was issued after oral argument but before decision in this case.6
The Commission has rendered its final orders implementing the terminal equipment registration program. First Report and Order in Docket No. 19528, 56 F.C.C.2d 593 (1975); Second Report and Order in Docket No. 19528, 58 F.C.C.2d 736 (1976) [hereinafter denominated as First Report and Second Report]. Pursuant to section 402(a) of the Communications Act, 47 U.S. C.A. § 402(a) (1962), and section 2342(1) of Title 28, petitioners — most of whom are telephone companies (carriers) or state utility commissions — contest the validity of the FCC’s registration program. The numerous claims made by petitioners can be systematically analyzed under three rubrics:
(1) allocation of power — does the FCC, as opposed to state regulatory commissions, have statutory authority to control customer interconnection when the “facilities” (i.e., the terminal equipment) attached to the national network are themselves used over 97% of the time for local, as opposed to interstate, communication;
(2) delegation of power — assuming FCC jurisdiction over joint terminal facilities, does the Communications Act give the Commission power to impose a registration program, to include the carriers in it, and to indirectly regulate non-carrier-affiliated manufacturers of terminal equipment; and
(3) exercise of power — assuming the FCC possesses the authority to do what it proposes, has the Commission exercised that authority in accordance with procedures required by law.
III. ALLOCATION OF POWER BETWEEN THE STATES AND THE FCC
A. Reconsideration Considered. —Petitioners mount their first assault over old terrain: they contend that sections 2(b)(1) and 221(b) of the Act expressly deny the FCC jurisdiction over equipment used “predominantly” in local communication.7 Seizing on the word “nothing” in sections 2(b)(1) and 221(b), petitioners contend that these reservation clauses override any potentially contrary language elsewhere in the statute. Respondents counter by invoking the doctrine of stare decisis and this Court’s policy of interpanel accord.8
It is true that North Carolina I rejected the jurisdictional challenge that petitioners press here; stare decisis would normally bar a reprise. “But stare decisis is a principle of policy and not a mechanical formula of adherence to the latest decision, however recent and questionable.” Helvering v. Hallock, 309 U.S. 106, 119, 60 S.Ct. 444, 451, 84 L.Ed. 604 (1940) (Frankfurter, J.) In the special and novel circumstances *1045of this case, which implicates significant state and federal interests and which involves questions of statutory interpretation that have been considered by no other Court of Appeals, we conclude that stare decisis does not preclude reconsideration of our holding in North Carolina I. The mere fact that a prior opinion exists is not sufficient in itself to call the doctrine of stare decisis into play: otherwise one rogue opinion could deprive the law of the accumulated expertise that stare decisis strives to safeguard.
If the rule of interpanel accord serves a purpose different from that of stare decisis, its purpose must be to allocate decisionmaking power between coequal panels subject to reversal by the Court of Appeals en banc. Because en banc review in this case is prevented by disqualification of all but one of the active Judges of this Court, strict application of the rule of interpanel accord seems unwarranted. We therefore reach the merits of petitioners’ jurisdictional challenge.
B. The Scope of Section 221(b). —Section 221(b) of the Act, 47 U.S.C.A. § 221(b) (1962) provides:
“[Njothing in this chapter shall be construed ... to give the Commission jurisdiction, with respect to practices, services, facilities or regulations for or in connection with . telephone exchange service even though a portion of such exchange service constitutes interstate or foreign communication, in any case where such matters are subject to regulation by a State commission or local governmental authority.”
(Emphasis added.)
The term “telephone exchange service” is a statutory term of art, and means service within a discrete local exchange system, see 47 U.S.C.A. § 153(r); compare 47 U.S.C.A. § 153(s) (definition of “toll,” or long distance, service). As we pointed out in North Carolina I, the legislative history of section 221(b) leaves no doubt that the purpose of section 221(b) is to enable state commissions to regulate local exchange service in metropolitan areas, such as New York, Washington or Kansas City, which extend across state boundaries. 537 F.2d at 795 & n.11. On this appeal, petitioners do not object to that determination, apparently agreeing with our view that “by force of section 221(b) a local carrier that serves a single multi-state exchange area is assured whatever degree of freedom from federal regulation section 2(b) provides for uni-state carriers and intrastate telephone business generally,” 537 F.2d at 795. Section 221(b) simply does not apply to the “facilities” with which this appeal is concerned.
C. The Scope of Section 2(b)(1). — Section 2(b)(1) of the Act, 47 U.S.C.A. § 152(b)(1) (1962), provides:
“[NJothing in this chapter shall be construed to . give the Commission jurisdiction with respect to practices, . . . facilities, or regulations for or in connection with intrastate communication service . . ..”
(Emphasis added.)
North Carolina I correctly reasoned that if section 2(b)(1) were construed to give the states primary authority over joint terminal equipment, i.e., equipment used interchangeably for interstate and intrastate service, then — whenever state regulations conflicted with federal rules applicable to interstate calls — the FCC would necessarily be prevented from discharging its statutory duty under sections 1 and 2(a) to regulate interstate communication. Petitioners’ emphasis on the word “nothing” in section 2(b)(1) is an attempt to employ a definitional stop to prevent the Court from reaching North Carolina Ts otherwise dispositive argument. Essentially, petitioners contend that the statute itself mandates state control over jointly used terminal equipment, and that therefore no possible duty of the FCC with respect to interstate communication can be compromised.
Petitioners’ argument begs the question. Even if the word “nothing” overrides any contrary language, the argument fails to identify those “intrastate” facilities over which state jurisdiction is to be primary. The question is whether jointly used facili*1046ties are to be classified for jurisdictional purposes as the “interstate” facilities of sections 1, 2(a) and 3(a), or as the “intrastate” facilities of section 2(b)(1). Sections 1, 2(a) and 3(a) commit jurisdiction over facilities utilized in interstate communication to the FCC. Section 2(b)(1) does not deny the FCC jurisdiction with respect to interstate facilities: it excludes only intrastate facilities from FCC jurisdiction. The terminal equipment dealt with in the order appealed from is used for both interstate and intrastate communication. The withdrawal of jurisdiction over one cannot be read to mean the withdrawal as to the other. Based on the statutory policy of centralizing control over interstate communications in the FCC, the otherwise plenary jurisdiction conferred by sections 201 — 205, and the recognition by section 410(c) of federal supremacy in rate base allocation, we concluded in North Carolina I that the “intrastate” facilities of section 2(b)(1) were those facilities “separable from and . . . not substantially affectpng] the conduct or development of interstate communications,” 537 F.2d at 793. Congress’ use of the word “nothing” in no way detracts from this analysis, nor does it suggest — as do petitioners — that the “intrastate” facilities of section 2(b)(1) are those items of terminal equipment used “predominantly” for local communication.
Petitioners confuse the fact that almost all terminal equipment is and has been used predominantly for local communication, with the statutory division of decisionmaking power. We find it difficult to credit an argument which amounts to an assertion that Congress created a regulatory scheme that depends on the calling habits of telephone subscribers to determine the jurisdictional competence of the FCC versus state utility commissions. There can be no doubt that, when the Communications Act was passed, Congress envisioned circumstances in which the same equipment would be employed for both interstate and local communication: section 221(b)’s special provisions governing multistate local exchanges are testimony enough. Particularly revealing, therefore, is the fact that although Congress secured to the states control over multistate exchanges “even though a portion of such exchange service constitutes interstate or foreign communication,” 47 U.S.C.A. § 221(b), it included no similar language in the reservation clause of section 2(b)(1). Section 2(b)(1) does not deny the Commission jurisdiction with respect to interstate facilities “even though a portion of the use of such facilities is for interstate communication.” Indeed, the language of section 221(b) is a reproach to petitioners’ construction of section 2(b)(1). The explicit language of section 221(b) shows that when Congress meant to give primary authority over inter- and intra-state facilities to the states, it was capable of unambiguously expressing that purpose.
A brief consideration of the potential consequences of state control over jointly used terminal equipment confirms our interpretation of section 2(b)(1). Surely petitioners would not contend that if a state commission authorized interconnection of a terminal equipment device which actually interfered with the transmission of interstate communications, the FCC would be powerless to order the removal of the device. And once it is recognized that FCC regulations must preempt any contrary state regulations where the efficiency or safety of the national communications network is at stake, there can be little argument that FCC regulation of jointly used terminal equipment for the purpose of improving or expanding interstate communication services may not also displace conflicting state regulations. The aim of the Communications Act, after all, is not limited to achievement of a minimally efficient, nondangerous national network. Instead, Congress has declared its purpose to be the creation of “a rapid, efficient, Nationwide, and world-wide wire and radio communication service with adequate facilities at reasonable charges.” Communications Act § 1, 47 U.S.C.A. § 151. If it is admitted — as we think it must be — that the FCC has full statutory authority to regulate joint terminal equipment to ensure the safety of the national network, then we can discover no *1047statutory basis for the argument that FCC regulations serving other important interests of national communications policy are subject to approval by state utility commissions.
D. The Implications of Federal Control Over Interconnection. — Petitioners characterize the registration program as an assumption of power similar to that given the Interstate Commerce Commission by the “Shreveport Doctrine” of Houston, East & West Texas Railway v. United States, 234 U.S. 342, 34 S.Ct. 833, 58 L.Ed. 1341 (1914), a result that Congress sought to avoid in drafting the Communications Act. In the Shreveport case, Louisiana shippers were shut out of Texas markets by a system of intrastate rates under which rates for shipments by interstate carriers eastward from Dallas and Houston to points in Texas were set to undercut ICC rates for shipment by the same carriers over the same distances westward from Shreveport into Texas. The Supreme Court held that the ICC was not limited to lowering the interstate rates as a remedy for the discrimination against interstate commerce worked by the Texas rate system. To so limit the ICC, the Court reasoned, would force the ICC to stultify its own judgment as to reasonable interstate rates. The ICC was therefore given the alternative of suspending the Texas intrastate rates, thus enabling the carriers to raise local rates to federal levels for similar distances. Despite a proviso in the ICC legislation similar to the jurisdictional reservation of section 2(b)(1) of the Communications Act, the Supreme Court held that the state power over exclusively local rates was inviolable only where local rates, in comparison with interstate rates, did not create unreasonable discriminations against interstate commerce. 234 U.S. at 357-58, 34 S.Ct. 833.
Petitioners correctly point out that in enacting the Communications Act, Congress sought to deny the FCC the kind of jurisdiction over local rates approved by the Shreveport Rate Case. We do not agree, however, that the registration program is some sort of regulatory atavism. Congress’ dissatisfaction with the Shreveport doctrine was that it permitted the ICC to control the rates for exclusively local service because of the relationship between those rates and the interstate rates. But the FCC’s registration program in no way purports to prescribe charges for local services; state commissions remain unfettered in their discretion to set rates for all local services and facilities provided by the telephone companies. Shreveport dealt specifically with rates for services which were admittedly local in nature; this appeal concerns the definition of what services and facilities are “intrastate” and hence subject to state rather than federal control.
The Supreme Court’s recent decision in FPC v. Conway Corp., 426 U.S. 271, 96 S.Ct. 1999, 48 L.Ed.2d 626 (1976), is particularly instructive. Section 201(b) of the Federal Power Act, 16 U.S.C.A. § 824(b), gives the Federal Power Commission jurisdiction with respect to the sale of electric energy at wholesale in interstate commerce, but denies the FPC jurisdiction over retail sales. This limitation, the Supreme Court noted, was designed to ensure that the Shreveport doctrine would not be employed to expand FPC jurisdiction:
“[T]he legislative history . . . indicates] that the section was expressly limited to jurisdictional sales to foreclose the possibility that the Commission would seek to correct an alleged discriminatory relationship between wholesale and retail rates by raising or otherwise regulating the nonjurisdictional, retail price.”
426 U.S. at 277, 96 S.Ct. at 2003 n.5.
In Conway, the FPC contended that its lack of jurisdiction over retail sales not only prevented it from regulating retail rates to correct unreasonable discriminations against customers, but also precluded FPC action to change wholesale rates because of an alleged discriminatory or anticompetitive relationship between wholesale and retail sales. A unanimous Supreme Court held to the contrary, and affirmed the judgment of the Court of Appeals that the FPC was not precluded from adjusting wholesale rates as a means of responding to the prob*1048lem of a discriminatory relationship between wholesale and retail rates. The jurisdictional limitation inspired by Congressional reaction to the Shreveport doctrine, said the Court, meant only that the FPC could not set retail rates as a means of dealing with the problem.
The lesson of FPC v. Conway Corp., in the circumstances of the instant case, is that the FCC has jurisdiction to prescribe the conditions under which terminal equipment may be interconnected with the interstate telephone line network. The FCC has not attempted to control the use of terminal equipment in local communication because of the effect that such use — through the medium of the market — has on interstate communication. Instead, the FCC has established a registration program governing the interconnection of terminal equipment when that equipment is used directly to effectuate interstate communication.
Petitioners counter by claiming that the effect of federal control of interconnection with respect to the national network will be to deprive the states of “meaningful” rate-making power. The state commissions contend that they currently subsidize residence and one-phone consumer service by charging more for business equipment (PBX’s and key phones) and for extension phones than the unit costs of such equipment. Apparently, the state commissions fear that increased substitution ofu independently provided terminal equipment for carrier-supplied equipment will reduce revenues and the corresponding amount of money available to subsidize other services and facilities.
We hold that the registration program— as a jurisdictional matter — does not jeopardize state ratemaking prerogatives to subsidize favored types of service. The states remain free to approve the pricing of carrier-supplied terminal equipment above or below unit cost. The effect of the federal program will depend upon the extent to which independents invade the terminal equipment market and undersell the regulated price. But cross-subsidization can still be accomplished by differential charges for services where there is no competition. For example, state commissions can permit carriers to classify and bill business line exchange service at rates higher than private line service if they desire to subsidize the latter.
Recognition of federal primacy in the regulation of jointly used terminal equipment no more curtails state ratemaking power as a matter of statutory jurisdiction than would the denial of state authority to set rates for interstate calls in order to subsidize local exchange and intrastate services. In the end, the problem of subsidy reduces to the tactical problem of obtaining sufficient revenues to cover the difference between the cost of providing subsidized service and the regulated price of subsidized service. Whether that amount is obtained by overcharging on PBX’s, by overcharging on business phone exchange service, or even by direct legislative appropriation, is largely academic as far as statutory jurisdiction is concerned. Political expediency may encourage state commissions to defend their current option to bury subsidy costs in as many holes as possible, but this concern cannot be allowed to determine the allocation of jurisdictional competency between state and federal agencies.
To support their retention of “meaningful” ratemaking power, petitioners resort to the science of statutory interpretation. No part of a statute, they argue, should be read in a fashion that makes it “meaningless”9; and to establish FCC authority over jointly used terminal facilities as primary would, according to petitioners, render the term “facilities” in section 2(b)(1) meaningless.
Reliance on the maxim of meaningfulness is misplaced in the circumstances of this case. First, the maxim is only a guide for interpretation when analysis of statutory purpose fails to resolve a dispute about *1049statutory meaning,10 and carries little weight against the major policy arguments favoring FCC jurisdiction and the Commission’s consistent assertion of FCC authority over jointly used equipment. Moreover, the maxim seems inappropriate to the construction of boilerplate language in an extremely general delegation statute. Finally, the Commission’s construction makes the term “facilities” meaningless not because exclusively intrastate facilities cannot be built or imagined (indeed, some are already in existence), but because state commissions prefer to avoid the economic and political costs of forcing the general consumer to buy two sets of terminal equipment.
E. Agency Estoppel. — It is true that most practices regarding terminal equipment have historically been regulated by the states, and that the FCC has always formulated its decisions in terms of equipment used for “interstate communication.” Petitioners contend that these facts establish an FCC interpretation of the statute which should now be held to bar FCC jurisdiction over jointly used terminal equipment.
While we agree that an agency’s construction of its enabling statute is entitled to deference from the courts, we have a good deal of difficulty with the more sweeping proposition that an agency is forever bound by its own prior view of its jurisdiction. Such a rule would not only be antithetical to the policy rationale for administrative agencies (ability to tailor broad legislative directives to fit specific problems), but would also contradict the central assumption of the rule respecting an agency’s construction of its enabling statute. That assumption is that the agency’s accumulated expertise makes it particularly well qualified to determine how the legislature might have dealt with a particular fact situation had that situation been among the conceptual paradigms to which the general language of a statute speaks. Petitioners’ proffered rule of agency estoppel would confound that assumption by preventing an agency from revising its approach to problems on the basis of experience in dealing with the range of disputes generated by particular configurations of statutory powers and duties.
Moreover, agency estoppel could hardly be enforced on the facts of this case. FCC decisions not unexpectedly refer only to the use of equipment for “interstate communication,” but the relevant cases firmly establish the Commission’s view that when facilities are used for both interstate and local communication, state regulations must give way to federal regulations even though the latter unavoidably affect local communication in the process of regulating interstate communication. Thus in AT&T (Railroad Interconnection), 32 F.C.C. 337, 339 (1962), the FCC ruled that “there is no.doubt that this Commission has jurisdiction over [local] exchange facilities to the extent that such facilities are used in accomplishing interstate toll communication.” In cases involving the attachment of special mouthpieces to telephones,11 the interconnection of radio base stations and telephone lines,12 the attachment of recording devices to telephones,13 the use of automatic answering *1050devices,14 the connection of teletypewriter equipment to the telephone network,15 the regulation of the interconnection of right-of-way telephone lines and the national telephone network,16 the control of the use of the telephone network for illegal purposes,17 and the interconnection of military communications lines with the national network,18 the FCC has never considered its jurisdiction inadequate because effectuation of the federal policy of interconnection might — as a practical matter — make enforcement of less liberal state rules difficult if not impossible. Additional reference to history would be otiose. The vast majority of terminal equipment has been — and is — regulated by the states, but the FCC has never conceded that joint equipment is beyond federal jurisdiction should the need for federal action arise.
IV. DELEGATION OF POWER
Assuming but not conceding that the FCC possesses statutory jurisdiction over jointly used terminal equipment, petitioners argue that the registration program exceeds the FCC’s statutory power over interstate carriers, and amounts to an impermissible assumption of power over non-carrier-affiliated manufacturers. Petitioners also object to required registration of carrier equipment because (1) authority for a registration program is not explicitly delegated by the Communications Act; (2) prior versions of section 215 granting a much broader power to investigate the “equipment” furnished to carriers, were not enacted; (3) FCC attempts to force AT&T to seek prior Commission approval before filing tariffs have been declared unlawful by the courts; and (4) the FCC has — until the present— never claimed the power to require registration of carrier equipment.
A. Independent Manufacturers —We consider as no more than makeweight petitioners’ claim that the registration program constitutes an impermissible regulation of independent manufacturers. That economic incentives may induce independent manufacturers to comply in order to compete effectively with registered products is immaterial: specifications for railroad rolling stock (which are directly applicable to carriers) under the Safety Appliance Acts have never been thought to constitute unlawful regulation of suppliers of rolling stock. We cannot see how the registration program — which tells a customer *1051which types of devices may be directly attached to the national network without the intermediary CAs and NCSUs — can be seen as an unlawful attempt to, regulate independent manufacturers. All manufacturers of terminal equipment, including the carriers and their subsidiaries, are free to register their equipment or not in accordance with their perceptions of economic self-interest.
In essence, what petitioners are attempting is the preservation of the carriers’ private lawmaking authority over independent manufacturers. Present tariffs proposed by carriers permit interconnection without the use of CAs and NCSUs in cases where certain carrier-initiated attestation procedures are followed by manufacturers. Other carrier-initiated tariffs permit and sometimes require interconnection of non-carrier-supplied equipment in remote and/or hazardous areas. And the conditions under which right of way companies may interconnect with the national network are established by carrier-promulgated tariffs.19 Surely it is anomalous for the carriers to invoke FCC authority to enforce these tariffs which regulate the use of private equipment, and yet deny that the Commission can prescribe carrier practices (as it clearly can under section 205) merely because such FCC action will have the effect of inducing private equipment manufacturers to alter the technical specifications of their products.
B. Carrier Inclusion. — The contention that the absence of explicit statutory authorization prevents the FCC from adopting a registration program contradicts all relevant authority20 and confounds the very purpose of agency delegation — institutionalization of authority to fashion policies and programs that implement broad legislative mandates in presently unforeseeable circumstances.21 The early versions of section 215 were designed to limit the anticompetitive potential of carrier-supplier contracts and practices. The fact that these prior versions were not enacted represents, at most, a congressional determination to leave antitrust enforcement to the Justice Department, and certainly does not reveal some sort of inchoate limitation on the FCC’s power to control the equipment attached by carriers to the national network. The fact that the FCC has not previously attempted to control directly the carriers’ equipment does not mean that the Commission has interpreted the Act to deny it jurisdiction over carrier equipment. Even if the principle that an agency’s construction of its enabling statute is entitled to deference, could be employed to estop an agency from revising its views (a proposition of not inconsiderable difficulty),22 the principle is inapposite to the facts of this case.
Sections 203 through 205 do prescribe a procedure for review and approval of tariffs by carriers, but section 205 itself gives the Commission power to determine and set just and reasonable charges and practices if it finds present tariffs to be unreasonable. The FCC may not exercise this authority unless it first provides interested parties “full opportunity for hearing,” see 47 U.S.C.A. § 205(a), but there is no contention that this requirement has not been met in this case. Thus, the instant case is not governed by the holding of the *1052United States Court of Appeals for the Second Circuit that the FCC could not require AT&T to obtain its approval before filing a carrier-initiated rate revision. See AT&T Co. v. FCC, 487 F.2d 865 (2d Cir. 1973). That case was based on the holding that the prior approval scheme contravened the express procedural dictates of sections 203 and 204. The FCC’s registration program, however, has been established under section 205 authority and in no way attempts to alter the procedure by which carriers file tariffs under sections 203 and 204.
V. EXERCISE OF POWER: CONSIDERATIONS OF ECONOMIC IMPACT
We have reaffirmed our decision in North Carolina I that the Communications Act grants the FCC, rather than the states, primary authority over terminal equipment used for both interstate and local communication (Part III, supra). We have determined that the powers delegated to the Commission by the Act include the power to establish a registration program for all terminal equipment (Part IV, supra). We turn now to petitioners’ third claim — that the FCC, even if it should be held to have the jurisdictional competence and the statutory authority to adopt a registration program for joint terminal equipment, has failed to exercise that power in a lawful manner.
Petitioners make two main objections. First, they claim that the FCC erroneously concluded that the public benefits of interconnection under a registration program would be greater than the cost of the registration program. Second, petitioners contend that the FCC neglected to consider the economic impact of its registration program, and that such an evaluation must be completed before the registration program can be put into effect.
A. Program Cost. — Our inquiry here focuses on the cost of the registration program itself, i.e., the cost to carriers and independent manufacturers of complying with the program’s administrative requirements. We do not, at this point, address the program’s economic impact on carrier revenue sources.
At first glance, petitioners’ position appears to be that the FCC incorrectly estimated the cost of compliance with its registration program. Yet petitioners point to no evidentiary irregularities or omissions that flawed the Commission’s deliberations. What petitioners actually attack is the FCC’s judgment that the costs of the program will be “minimal,” First Report ¶ 20 & n.10; see also Second Report ¶¶ 12-13, and the FCC’s conclusion that the public benefits of liberalized interconnection under a registration program will exceed the costs of implementing and complying with that program. First Report ¶ 6.
Petitioners emphasize the projected costs of registration, but this misapprehends the office of judicial review of agency action. The absolute cost of a registration program does not determine its lawfulness. To be sure, the registration program involves expenses which terminal equipment manufacturers currently avoid, but increased expenses inevitably accompany any regulation of industry. The question for the Commission is whether the public benefits of a registration program outweigh the costs. The question for the Court is whether the FCC’s judgment is supported by substantial evidence.23
Even if petitioners’ protestations about registration costs are fully credited,24 peti*1053tioners suggest no reason to suspect that the Commission’s decision was fundamentally defective or not supported by substantial evidence. Indeed, the specifics of the program — type registration, simplified registration for equipment currently in use, and grandfathering of almost all carrier equipment — should ensure that expense will be held to the minimum consistent with any registration program. If a manufacturer finds registration too burdensome, it can continue the current practice of selling equipment for attachment using carrier-supplied CAs and NCSUs. Moreover, the record shows that, in response to carrier suggestions, the FCC streamlined its registration requirements, thereby reducing the cost of registration (according to carrier figures) by an estimated 250 million dollars.25 We see no institutional impediment to continued cooperation between the FCC and the carriers to keep registration expenses to a minimum.
In designing its registration program, the Commission has fully evaluated petitioners’ cost projections. Petitioners’ claims amount to no more than a quarrel with the Commission about where the public interest lies. Because petitioners fail to show any defects in the process by which the Commission made its decision, it would be a naked assertion of judicial power for this Court to reverse the Commission’s determination that the registration program will further the public interest. On this record, there is no warrant for upsetting the Commission’s judgment, and we must therefore respect it.
B. Economic Impact. — Petitioners argue that the registration program will cause significant decreases in carrier revenues as customers purchase independently manufactured terminal equipment rather than renting carrier-supplied equipment. The loss of revenues from terminal equipment, they contend, will in turn force major changes in rates for residential service presently subsidized by prices for terminal equipment which are above unit cost. Petitioners allege that the Commission has not even considered the possible economic impact of its registration program, and that an extensive analysis of economic impact must be completed before the program can lawfully be put into effect.
1. A Perspective on Controversy. — A fundamental error infects petitioners’ analysis of economic impact: they confuse the economic impact of the interconnection policy, which has been in effect since 1969, with the economic impact of the registration program. Since 1969, carrier-filed tariffs have permitted all subscribers to purchase any type of terminal equipment from independent manufacturers and attach that equipment to the telephone line, as long as the carrier-supplied CAs and NCSUs are employed.26 The only difference between the registration program and the current tariffs is that under the program customers will be permitted to attach registered terminal equipment without paying the carriers for CAs and NCSUs.27
Petitioners do not challenge the legality of the FCC’s interconnection policy, and apparently they do not contend that the *1054current carrier-filed “connecting arrangement” tariffs must be suspended while an in-depth study of their economic impact is completed. Therefore, in assessing the economic impact of the registration program, we must focus on the economic effects of the elimination of CAs and NCSUs only.
2. Revenue Losses. — The contention that elimination of CAs and NSCUs will cause direct revenue losses is unfounded. The carriers have consistently maintained that prices currently charged for CAs and NCSUs no more than recoup their costs of providing the intermediary devices.28 Thus, if the intermediary devices were eliminated, the carriers would suffer no net decline in revenues, according to their own figures. Nor would the carriers’ ability to compete with independent sellers of terminal equipment be directly impaired by elimination of the intermediary devices: since these devices are currently priced at cost, they provide no excess revenue to underwrite competition in terminal equipment. In short, elimination of CAs and NCSUs will have no different direct economic impact than the present “connecting arrangement” tariffs.
It might be argued, however, that elimination of CAs and NCSUs will indirectly reduce carrier revenues because independent terminal equipment can be purchased and used at a lower cost to the customer under the registration program. That is, the customer will no longer have to pay the price of the terminal equipment plus the cost of the intermediary devices, and carriers will face the unpleasant alternative of either losing sales or lowering prices on terminal equipment.
Two difficulties beset this argument. First, it makes the illogical assumption that independents can manufacture equipment that will perform the functions currently performed by CAs and NCSUs (a precondition for registration) without a commensurate increase in costs.29 Second, it postulates a kind of price-sensitive competition that petitioners’ own facts belie. Petitioners tell us that they presently overcharge on sophisticated terminal equipment in order to subsidize residential service, yet they are unable to show that, under the interconnection policy in effect since 1969, this practice has resulted in diminished sales of terminal equipment. The logical conclusion is that even if increases in independents’ costs (and prices) do not equal the price of CAs and NCSUs, the registration program can hardly be expected to cause a significant “substitution effect.” Should independents choose to cut prices or engage in significant nonprice competition, any economic impact from such tactics would properly be attributed to the interconnection policy which ended the carriers’ monopoly over terminal equipment, and not to the registration program.
C. The Necessity for Prior Economic Analysis. — Petitioners insist that the Commission must make a thorough study of all possible economic impacts before the program can be put into effect. We hold that the statutory prerequisites for FCC action have been met, and reject petitioners’ attempt to characterize the Commission’s position as a refusal even to consider potential economic impact.
Contrary to petitioners’ assertions, no general principle of administrative law forces all agencies to conduct exhaustive economic impact studies before taking action. Such a requirement would hamstring administration at every juncture of the policy making and implementation process. Rather, the prerequisites for agency action — as a fair reading of the cases cited by petitioners reveals — are enumerated by each agency’s enabling statute.
*1055Section 205(a) of the Communications Act, 47 U.S.C.A. 205(a) (1962), provides:
“Whenever, after full opportunity for hearing . . . the Commission shall be of opinion that any charge, classification, regulation or practice of any carrier or carriers is or will be in violation of any of the provisions of this chapter, the Commission is authorized and empowered to determine and prescribe what will be the just and reasonable charge . and what classification, regulation, or practice is or will be just, fair and reasonable, to be thereafter followed . . .
The unreasonableness and discriminatory effect (in violation of sections 203 and 204) of the present “connecting arrangement” tariff is established and is not challenged on this appeal. Therefore, all explicit statutory prerequisites for Commission action to prescribe carrier practices have been fulfilled.
We would be remiss, however, if we permitted the FCC to implement a registration program that would have major effects on rates paid by telephone subscribers without even considering that potential economic impact. The purpose of the Communications Act — to establish “a rapid, efficient, Nationwide and world-wide wire and radio communication service with adequate facilities at reasonable charges,” 47 U.S. C.A. § 151 (1962) — would be undercut if the Commission could adopt “technical” requirements without making a preliminary reasoned assessment of their economic impact. On the other hand, section 151 would be equally frustrated if the Commission were barred from acting unless it first performs an in-depth economic analysis of every decision it must make and every program it adopts.
We reject, as inconsistent with section 205, petitioners’ contention that the Commission must complete a full-scale economic inquiry before implementing its registration program. While the Communications Act secures a major role for carriers in the filing of binding tariffs, see 47 U.S.C.A. §§ 203 — 204 (1962), section 205 clearly permits the Commission to prescribe carrier practices and regulations when carrier-filed tariffs are determined to be in violation of the substantive requirements of the Act. Petitioners’ argument not only ignores this express authority granted by section 205 to the FCC, but would produce the anomalous result that an admittedly illegal carrier-filed tariff would remain in effect pending completion of an economic inquiry concerning a presumptively legal FCC regulation.
Nor can we subscribe to petitioners’ claim that the Commission has refused to consider the economic impact of the registration program. The Commission has consistently maintained that the registration program will have an economic impact that is not substantially different from the impact of the present “connecting arrangement” tariffs. Consequently, the Commission views Docket 19528 as limited to the “technical” aspects of registration, although it continues to investigate the long-term economic impact of the interconnection policy in Docket 20003.30
If the registration program posed a major threat to carrier revenues, the Commission, of course, could not blink reality and assume the impact away. But it is equally true that petitioners cannot create an economic impact with the volume of their jeremiad. Their claims of economic impact are refrains of assertions that the FCC has *1056consistently found to be unsubstantiated by evidence, conclusory, and based on unrealistic assumptions about market behavior. See Carterphone, 14 F.C.C.2d at 573 & n. 3; Notice of Inquiry in Docket 2003, 46 F.C. C.2d 214; Customer Interconnection, 49 F.C.C.2d 1238, 1239. Our own analysis of the potential impact of the registration program, see part VB, supra, satisfies us that the Commission’s operational assumption that replacing CAs and NCSUs with a registration system will have minimal economic impact, is sound. We can discover no statutory requirement that compels the Commission to test this assumption in time-consuming additional proceedings.
We repeat that the Commission has not denied its responsibility to consider the economic impact of its registration program. What the FCC has done is to make reasonable assumptions about economic impact based on the evidence currently available. The Commission’s recognition of its responsibility to consider economic impact is evidenced by its announced policy of granting appropriate relief to carriers who can show injury from liberalized interconnection. In Mebane Home Telephone Co., 53 F.C.C.2d 473, 480 (1975), the FCC provided that restraints on interconnection will be authorized whenever a carrier files a petition and demonstrates that “compliance with the obligation . . . has already resulted in or will result in direct, substantial and immediate economic injury to [the] telephone system and detriment to the public interest.” (Emphasis added.)
This exemption from the FCC’s interconnection policy and the proposed registration program seems adequate protection for the carriers as institutions, and for the public interest if it be implicated by any substitution effect. To further delay effectuation of the registration program would be an excess of caution. This is particularly true in the circumstances of this case, where the alternative to permitting the FCC’s program to go into effect is to allow the carriers to continue to operate under their “connecting arrangement” tariffs which are themselves unlawful.
The Commission’s First Report and Order in Docket No. 19528, 56 F.C.C.2d 593 (1975); its Second Report and Order in Docket No. 19528, 58 F.C.C.2d 736 (1976), and its Memorandum Opinion and Orders released February 13, 1976, March 15, 1976, and April 28, 1976, are affirmed.