OPINION OF THE COURT
Pursuant to section 10(e) of the National Labor Relations Act (“Act” or “NLRA”), 29 U.S.C. § 160(e) (1976), the National Labor Relations Board (“Board”) has petitioned this court for enforcement of its order issued on September 30, 1981.1 In its decision accompanying that order the Board held that the Cardox Division of the Chemetron Corporation (“Company”) had violated sections 8(aXl) and 8(a)(5) of the Act, 29 U.S.C. §§ 158(a)(1), (a)(5) (1976), by refusing to bargain with and by withdrawing exclusive recognition of Teamsters Union Local No. 115 (“Union” or “Local 115”). The Board failed, however, to determine under section 9(b) of the Act, 29 U.S.C. § 159(b) (1976), whether the bargaining unit identified by the parties was an appropriate unit for collective bargaining purposes. For that reason we will deny the Board’s application for enforcement and will remand this action to the Board for further proceedings consistent with this opinion.
FACTS
A.
The Cardox Division of the Chemetron Corporation is engaged in the manufacture, sale, and distribution of carbon dioxide. The Company operates approximately fifty *150separate facilities located throughout the United States, including ten manufacturing plants and forty distribution depots. The present controversy arises within the Company’s “Eastern Region” which covers the northeastern portion of the United States from the Virginia-North Carolina state line to the Canadian border.
The Company has four regional servicemen in the Eastern Region, each assigned to a designated field service area. These servicemen are Charles Pennington, whose service area includes Virginia, Maryland, and a small part of southern Pennsylvania; James Hurley, whose service area includes eastern Pennsylvania, southern New Jersey, and all of Delaware; Richard Gerber, whose service area includes Bridgeport and New Haven, Connecticut, and the metropolitan New York-Newark area; and Tom Shane, whose service area includes eastern upstate New York, Maine, central New Hampshire, Massachusetts, and a portion of Connecticut. The servicemen work from their homes, primarily answering customers’ calls in their service areas. Their work assignments, however, are not limited to their particular assigned service areas, and they are frequently assigned to other areas on a temporary basis.
All four servicemen are paid on a salaried basis and have an identical package of fringe benefits. They are supervised solely by Bernard O’Reilly, the Company’s Service Manager for the Eastern Region. He approves their weekly time sheets and expense accounts, authorizes overtime, schedules their vacations, and handles their grievances. Although the servicemen are responsible for installing and maintaining equipment at some of the Company’s distribution depots, the depot managers have no authority to direct their hours or work schedule.
B.
On June 19 and July 2,1979, respectively, servicemen Pennington and Hurley signed cards authorizing the Union to represent them for the purposes of collective bargaining. On August 14 two Union representatives met with Dick Wyatt, the Company’s Delaware City, Delaware depot manager. They presented him with a letter and recognition agreement and requested that the Company recognize and bargain with the Union as the collective bargaining representative of the field servicemen employed at the facility.2 Wyatt read the letter, personally checked the authorization cards, and then signed the recognition agreement. The agreement was sent to John Manning, the Company’s Director of Employee Relations, who, after making some minor modifications, executed the agreement on August 27, 1979. The unit recognized within the agreement consisted of “field servicemen not included in any other bargaining unit and excluding guards, office clerical and supervisors as defined in the Act, employed by the Employer at [its Delaware City, Delaware] facility.” App. 263a-64a.
After some initial correspondence the parties held their first bargaining session on October 17, 1979, but failed to reach an agreement on a contract. A second meeting was later scheduled for December 5, 1979.
Sometime in November, Pennington informed O’Reilly that he no longer wanted to be represented by the Union. Pennington testified that he changed his mind because of a dispute with the union over whether he should work while another union, Teamsters Local 326, was out on strike. At about the same time Pennington began receiving his phone calls at the Company’s Suffolk, Virginia depot instead of at Dela*151ware City.3 When O’Reilly informed Hurley of Pennington’s decision about the Union, Hurley also decided that he no longer wanted to be represented by Local 115.
A few days before the bargaining session scheduled for December 5, Manning first learned that Pennington and Hurley had advised their supervisor that they no longer wanted to be represented by the Union and that Pennington was now receiving his phone calls at the Suffolk depot. After discussing the matter with counsel, Manning requested that O’Reilly obtain from both Pennington and Hurley confirmation in writing that they no longer desired to be represented by Local 115. In addition, Manning called the attorney for the Union and canceled the December 5 meeting. On December 6 Manning wrote a letter to the Union stating that only one employee, Hurley, now worked in its jurisdictional area4 and thus “there does not seem to be any reason to cover him under a Local 115 agreement.” A few days later the Company received the requested letters from Pennington and Hurley indicating their intention to withdraw from the Union.
PROCEEDINGS BELOW
The Union filed an unfair labor practice charge against the Company on December 12, 1979. On January 30, 1980, the General Counsel issued a Complaint and Notice of Hearing alleging that the Company had violated sections 8(a)(1) and 8(a)(5) of the Act by withdrawing exclusive recognition of the Union on December 6, 1979.5 In its answer the Company denied that it had committed any unfair labor practices.
A hearing was held before an Administrative Law Judge (“ALJ”) on July 10, 1980. At that hearing the Company argued that the unit identified by the parties in the voluntary recognition agreement was inappropriate because Pennington and Hurley lacked a community of interest distinct from that of the other servicemen. Alternatively the Company argued that the unit was inappropriate because it had been reduced in size to a single employee by December 6. Finally, the Company asserted that, even if the agreed upon unit was appropriate, at the time it withdrew recognition the Union no longer represented either of the two employees who comprised the purported unit. On September 24,1980, the ALJ issued a decision in which he accepted the Company’s argument that the agreed upon bargaining unit was inappropriate because it did not include all four field servicemen in the Company’s Eastern Region. Finding an “overwhelming showing of community of interest,” the ALJ held that it was inappropriate to carve out from the four servicemen any unit of less than four. App. at 20a-21a. Having found the unit inappropriate, the AU reasoned that the Company could not be held to have violated section 8(a)(5) of the Act and thus recommended that the complaint be dismissed in its entirety.6 The AU did not reach the merits of the Company’s other defenses.
On October 16, 1980, the General Counsel filed exceptions to the AU’s decision with the Board. The Company filed an answering brief but did not file any cross-exceptions to the findings of the ALJ.
On September 30, 1981, the Board issued a decision and order in which it found that the Company had violated sections 8(a)(1) *152and 8(a)(5) of the Act. 258 N.L.R.B. at 1204. The Board disagreed with the ALJ’s statement that, “[t]he threshold question presented in this proceeding is whether the ... unit ... is appropriate.”7 Instead it held that because the Company voluntarily recognized and bargained with the Union, it was unnecessary for the Board to decide whether an appropriate unit existed. 258 N.L.R.B. at 1203.8 Quoting from Arizona Electric Power Cooperative, Inc., N.L.R.B. 1132, 1133 (1980), the Board held that it could issue a bargaining order “covering a unit which it could not have initially certified under the Act” when the parties have knowingly and voluntarily bargained over that unit. 258 N.L.R.B. at 1203.
Having disposed of the Company’s argument that the unit was inappropriate, the Board then addressed the Company’s contention that it could withdraw recognition on December 6 because the Union no longer enjoyed the support of the two employees in the unit. The Board determined that, because a reasonable time for bargaining had not expired, the Union continued to enjoy an irrebuttable presumption of majority status when the Company withdrew recognition. Thus the Board held that the Company’s refusal to bargain violated section 8(a)(1) and section 8(a)(5) of the Act.
On October 23,1981, the Company filed a “Motion for Reconsideration, Reopening of the Record and for Stay of Board Decision and Order.” App. at 37a. The Company asked the Board to reconsider its decision and to review new evidence on whether the agreed upon unit had been permanently reduced to a single employee, if not prior to the time recognition was withdrawn, at least since the time of the hearing before the Administrative Law Judge in July 1980.9 On February 4, 1981, the Board denied the Company’s motion as “lacking in merit.” This action for enforcement followed.
DISCUSSION
I.
In asking this court to deny enforcement of the Board’s order, the Company asserts that the Board exceeded its statutory authority by refusing to make a unit determination as required by section 9(b) of the Act. The Company argues that absent such a determination, the Board had no statutory authority to find that the Company committed unfair labor practices under sections 8(a)(1) and 8(a)(5). Furthermore, the Company contends that the unit identified in the voluntary recognition agreement is in fact inappropriate because (1) the unit consists of only two of the four field servicemen in the Company’s Eastern Region and thus represents an arbitrary grouping, or (2) the unit has been permanently reduced to one employee and thus contravenes established Board policy.10
*153In response the Board asserts that voluntary recognition agreements are “a favored element of national labor policy,” NLRB v. Broadmoor Lumber Co., 578 F.2d 238, 241 (9th Cir.1978), and that having entered into such an agreement, an employer should not be allowed to unilaterally repudiate its recognition of a union. The Board contends that to hold otherwise “would fly in the face of [its] statutory obligation to promote stability in bargaining relationships.” 258 N.L.R.B. at 1203. Thus the Board argues that, in an unfair labor practice proceeding involving a voluntary recognition agreement, it is not required to determine that the agreed upon unit is appropriate.11
II.
Section 9(b) of the NLRA states in relevant part:
The Board shall decide in each case whether, in order to assure to employees the fullest freedom in exercising the rights guaranteed by this Act, the unit appropriate for purposes of collective bargaining shall be the employee unit, craft unit, plant unit, or subdivision thereof.
29 U.S.C. § 159(b) (1976) (emphasis added). Although under that provision the Board has broad discretion when making a unit determination,12 the section’s language expressly requires that the Board make a decision “in each case.” Big Y Foods, Inc. v. NLRB, 651 F.2d 40, 45-46 (1st Cir.1981); Long Island College Hospital v. NLRB, 566 F.2d 833, 840-41 (2d Cir.1977), cert. denied, 435 U.S. 996, 98 S.Ct. 1647, 56 L.Ed.2d 84 (1978); Memorial Hospital of Roxborough v. NLRB, 545 F.2d 351, 360 (3d Cir.1976); Crown Zellerbach Corporation, 246 N.L.R.B. 202, 203 (1979); see Allegheny General Hospital v. NLRB, 608 F.2d 965, 969 (3d Cir.1979). That legislative command is mandatory and constitutes a non-delegable duty imposed on the Board by Congress. Roxborough, 545 F.2d at 360. Accordingly the Board abdicates its statutory duty when it fails to exercise its discretion under section 9(b).
*154In Memorial Hospital of Roxborough v. NLRB, 545 F.2d 351 (3d Cir.1976), we denied enforcement of a Board order finding unfair labor practices under sections 8(a)(1) and 8(a)(5) because the Board failed to make a unit determination as required by section 9(b). In that case the Board had extended complete deference to a state agency’s prior determination of what was a proper unit for the purposes of collective bargaining among Memorial Hospital’s maintenance department employees.13 In denying enforcement we stated:
Congress has ... mandated Board determination “in each case” of “the unit appropriate” for collective bargaining. Thus the statute requires the Board to exercise its discretion as to an appropriate unit in each and. every case. This responsibility can neither be delegated to nor discharged by a state agency where Congress has sought to create a national labor policy by vesting this discretion in a national labor board. La Crosse Telephone Corp. v. Wisconsin Employment Relations Board, 336 U.S. 18, 24-27, 69 S.Ct. 379 [382-383], 93 L.Ed. 463 (1948). Here, however, the Board abdicated its required duty by accepting the [state agency’s] determination without exercising its own mandated discretion. In so doing the Board “overstep[ped] the law.” Packard Motor Car Co. v. NLRB, [330 U.S. 485,] 491, 67 S.Ct. 789, 793, 91 L.Ed. 1040 (1947)].
Roxborough, 545 F.2d at 360; see Allegheny General Hospital v. NLRB, 608 F.2d 965, 969 (3d Cir.1979); cf. Big Y Foods, 651 F.2d at 46 (a conclusive presumption that a unit is appropriate is invalid under section 9(b)).
Our reasoning in Roxborough applies with equal force in the instant case. Section 9(b) requires the Board to exercise its discretion and determine that the unit agreed upon by the parties is an appropriate unit for bargaining purposes. The Board can not simply defer to a voluntary agreement entered into by an employer and a union without making any assessment that the unit identified within the agreement is proper. To do so oversteps the law.14
We do not think that our decision in International Telephone and Telegraph Corp. v. NLRB, 382 F.2d 366 (3d Cir.1967), cert. denied, 389 U.S. 1039, 88 S.Ct. 777, 19 L.Ed.2d 829 (1968), leads to a contrary result. In that ease the Board conducted an original unit certification proceeding and election in 1951. One of the units certified was an engineer-technician unit. Under its then applicable policies the Board ruled that the technicians were properly included within the unit despite the fact that they might be “professionals.” The Board reached its conclusion because of the similarity of working conditions, integration of work, and parallel bargaining history of the technicians and the engineers. The Board also found that professional employees constituted a majority of workers within the unit regardless of how the technicians were classified. 382 F.2d at 369. The company did not seek review of the Board’s determination in the courts. Over the next thirteen years the parties entered into a series of collective bargaining agreements. Following a strike in 1964, however, the company withdrew recognition of the union as the representative of the professional employees. After a complaint was brought by the General Counsel the Board determined *155that the company’s actions violated sections 8(a)(1) and 8(a)(5) of the Act. 159 N.L.R.B. 1757 (1966). The Board recognized that its original certification might have been illegal, see Leedom v. Kyne, 358 U.S. 184, 79 S.Ct. 180, 3 L.Ed.2d 210 (1958),15 but held that, because the unit was not “inherently inappropriate,” 159 N.L.R.B. at 1764, it could still find the employer’s refusal to bargain over the unit violated the Act. This court enforced the Board’s order. We recognized that the original certification election might well have violated section 9(b)(1) of the Act.
382 F.2d at 370. We concluded that while the Board certification election might have been improper, in a situation where the “professional” group had existed and had functioned as a member of a consensual unit for collective bargaining purposes and where even after notice of illegality, the parties continued for a period of over thirteen years to engage voluntarily in collective bargaining, any error in the original determination of the bargaining unit could not justify a refusal to bargain. Id. Thus International Telephone and Telegraph is consistent with our holding that the Board must determine that the unit agreed to by the parties is not contrary to the Act or Board policy.16
But to concede that point is not to say that every unit composed of professionals and non-professionals originally formed without a separate election is invalid forever. Though section 9(b)(1) prohibits the Board from designating a mixed unit without holding the requisite election of professionals, nothing in the language of the Act prohibits the relevant parties from maintaining and recognizing such a unit consensually. Retail Clerks Union Local 324 (Vincent Drugs), 1963, 144 N.L.R.B. 1247. In our view such a consensual arrangement is presented here.
III.
We recognize that the fact that the parties have entered into a voluntary agreement changes the nature of the Board’s inquiry under section 9(b). As we stated in Roxborough:
[W]here the parties have stipulated to the appropriateness of a unit, the Board limits its review to determining that the unit *156does “not contravene the provisions or purposes of the Act [NLRA] or well settled Board policies.” Otis Hospital, Inc., 219 NLRB No. 55 (1975). See also St. Joseph Hospital & Medical Center, 219 NLRB No. 161 (1975).
Roxborough, 545 F.2d at 360 n. 11; cf. International Telephone and Telegraph Corp., 159 N.L.R.B. 1757, 1764 (1966) (unit not inherently inappropriate), enforced, 382 F.2d 366 (3d Cir.1967), cert. denied, 389 U.S. 1039, 88 S.Ct. 777, 19 L.Ed.2d 829 (1968). Thus in a voluntary recognition case, section 9(b) requires only that the Board make a determination that the unit agreed upon by the parties is not inconsistent with the National Labor Relations Act and past Board policy. In the instant case, however, the Board made no such determination. Absent such a finding, the Board lacks the statutory power to hold that the Company’s withdrawal from the voluntary bargaining agreement constitutes a section 8(a)(5) violation. Supreme Sugar Company, 258 N.L. R.B. 243, 245 (1981).17
Our reading of the statute is consistent with the Act’s underlying purpose of protecting the interests of all employees, as well as the interests of unions and employers. Review of voluntary recognition agreements by the Board prevents employers and unions from mistakenly agreeing to a unit which does not adequately protect the rights of all the workers in the workplace. Review also prevents a union and an employer, through a voluntary agreement, from manipulating the scope and composition of a bargaining unit for their own purposes. Cf. NLRB v. St. Luke’s Hospital Center, 551 F.2d 476, 483 (2d Cir.1976) (deference to state unit determination frustrates policy of employee self-determination). “The National Labor Relations Board is not just an umpire to referee a game between an employer and union. It is also a guardian of individual employees. Their voice, though still and small, commands a hearing.” Shoreline Enterprises of America, Inc. v. NLRB, 262 F.2d 933, 944 (5th Cir.1959). By exercising its discretion under section 9(b), the Board insures the protection of individual employees’ rights to self-organization and freedom of choice. Safeguarding those rights in turn effectuates the collective bargaining process. Kalamazoo Paper Box Corp., 136 N.L.R.B. 134, 137 (1962); J. Abodeely, The NLRB and the Appropriate Bargaining Unit 2 (1971).
This court recognizes the value of voluntary recognition agreements in the collective bargaining process. We also adhere to the basic policy that a company and a union must be held to their agreements if those agreements are consistent with the Act. See NLRB v. Lyon & Ryan Ford, Inc., 647 F.2d 745, 752 (7th Cir.1981); Shoreline, 262 F.2d at 943; Jerr-Dan Corp., 237 N.L.R.B. 302, 303 (1978), enforced, 601 F.2d 575 (3d Cir.1979). But we refuse to conclude that these policies compel the Board to merely accept private agreements without first determining whether those agreements are contrary to the Act or established Board policy.
Because the Board did not exercise its discretion as required by section 9(b), it acted outside its authority under the NLRA in issuing a bargaining order to the Company. Accordingly we will deny enforcement and will remand this action to the Board to determine whether the unit agreed upon by the parties is appropriate in light of the requirements of the Act and settled Board policy.18