All defendants were convicted in a non-jury trial for conspiracy to violate 18 U.S.C.A. §§ 1084 and 1952, which prohibit the use of interstate wire and telephone facilities to carry on illegal gambling operations. All defendants were similarly convicted of substantive violations of § 1952, and defendants Mastera-na and Doolittle were also convicted of substantive violations of § 1084. The convictions were obtained primarily by the use of conversations intercepted by a wiretap authorized by the district court under Title III of the Omnibus Crime Control and Safe Streets Act of 1968, 18 U.S.C.A. §§ 2510-2520, and the fruits of searches for which the wiretap provided probable cause. Recognizing that without this evidence the Government’s case would be substantially weakened, if not destroyed, defendants mounted a multifaceted assault on the wiretap in a motion to suppress the evidence in the district court. The district court denied the motion, and the convictions followed. The attack has been renewed in this Court, but like the district court, we find no infirmity warranting suppression of the evidence and affirm all convictions.
Defendants first attack the wiretap provisions of the Omnibus Crime Control Act as unconstitutional for violations of the First, Fourth, Fifth and Sixth Amendments. We have recently upheld this portion of the statute against a similar constitutional attack. United States v. Sklaroff, 506 F.2d 837 (5th Cir. 1975).
Next the defendants assert that various procedural irregularities in the authorization of the wiretap request within the Justice Department require that the evidence be suppressed. See 18 U.S.C.A. § 2515. The Supreme Court of the United States has ruled that irregularities of the kind asserted here do not render the communications “unlawfully intercepted” or the interception request “insufficient on its face.” United States v. Chavez, 416 U.S. 562, 94 S.Ct. 1849, 40 L.Ed.2d 380 (1974); see 18 U.S.C.A. §§ 2518(10)(a)(i), -2518(10)(a)(ii). At the time this case was argued, the Supreme Court had not decided Chavez and appellants relied on the Ninth Circuit decision in that case. United States v. Chavez, 478 F.2d 512 (9th Cir. 1973). The Supreme Court modified that portion of the Ninth Circuit decision upon which the appellants relied. We find nothing in this case to warrant a different result *1371than that determined by the Supreme Court in Chavez. Considering the other information contained in the Interception Order Authorization, such as the location of the phones to be tapped, address of the Sportsman’s Club, and its owner, we find the one incorrect digit in one of the four telephone numbers listed therein to be an immaterial variation from the actual, correct number for which the tap was requested of the district court. Cf. United States v. Chavez, supra.
The procedure of filing the affidavits of the Attorney General and his subordinates, as a method of proving the administrative history of the specific authorization in this case, is identical to that used in Chavez. There is no constitutional infirmity in the district court’s refusal to require more of the Attorney General on this narrow issue of fact.
Appellants contend that the use of a “pen register,” as in this case, is not specifically authorized by Title III and must, therefore, be considered rejected by Congress as an appropriate investigative tool. The Act does not prohibit the use of pen registers and we do not view its use in this case, based upon probable cause and with a separate authorization from the district court, as being constitutionally offensive. See United States v. Giordano, 416 U.S. 505, 553-554, 94 S.Ct. 1820, 40 L.Ed.2d 341 (1974) t(Powell, joined by the Chief Justice, and Black-mun and Rehnquist, JJ., concurring in part and dissenting in part); United States v. Finn, 502 F.2d 938 (7th Cir. 1974); United States v. Brick, 502 F.2d 219, 223 (8th Cir. 1974); cf. United States v. Falcone, 364 F.Supp. 877 (D.N. J.1973), aff’d, 500 F.2d 1401 (3rd Cir. 1974).
Certain defendants assert that the Government lacked probable cause to believe that their conversations would be intercepted by the wiretap. They con-, tend that this lack of probable cause should render the tap unlawful as to them. A similar argument has been rejected by the Supreme Court in United States v. Kahn, 415 U.S. 143, 94 S.Ct. 977, 39 L.Ed.2d 225 (1974). At oral argument, the appellants relied upon the Seventh Circuit decision in United States v. Kahn, 471 F.2d 191 (7th Cir. 1972). The reversal by the Supreme' Court of the Seventh Circuit decision is dispositive of the issue as framed here. The statute does not require that there be probable cause as to all persons whose conversations are intercepted. See 18 U.S.C.A. § 2518(l)(b)(iv). Since the wiretap in this case was validly issued, the wiretap conversations of those individuals not known to be involved in criminal activity at the time of the court authorization may be used against them.
The wiretap authorization referred to “Billy Cecil Doolittle and others as yet unknown.” Anderson and Baxter contend that the Government had reasonable cause to believe that their conversations would be intercepted. Relying on certain language in the Supreme Court’s opinion in Kahn, they argue that, not being “unknown,” they should have been named in the authorization. They contend that since they were not named, the wiretap order was illegal as to their conversations. The same argument could be made for Sanders. We reject this argument. The defendants neither allege nor demonstrate any prejudice to them in not being named in the authorization. The Government contends that its agents had personal knowledge, as opposed to information, to support probable cause as to illegal activity only of Doolittle, the co-owner of the Sportsman’s Club, the establishment wherein the telephones were located and to which the telephone bills were sent. All defendants received an inventory of the intercepted conversations, were allowed to listen to the tapes and received transcripts of the conversations prior to use against them at trial, as if they had been named in the order. Most of the conversations of each defendant were with Doolittle, the person named in the order. There is no indication of bad faith or attempted subterfuge by the Government in its wiretap application. The application and affida*1372vit delineated specifically the information expected to be gathered from the tap. We hold there was substantial compliance with the requirements of the Act, and that the failure to name other defendants does not render the evidence obtained as to them inadmissible under 18 U.S.C.A. § 2518(10)(a).
The last general attack by all defendants is that the wiretaps exceeded the scope of the interceptions authorized by the court order. The testimony by the monitoring agent at the suppression hearing reveals that they listened to each call only long enough to determine whether in their judgment it could be one dealing with gambling as authorized to be intercepted by the district court. Only those calls which the agents reasonably believed were related to gambling were recorded on tape. There is no question that some irrelevant and personal portions of gambling conversations were intercepted or that certain nonpertinent conversations were intercepted. But this is inherent in the type of interception authorized by Title III, and we do not view the simple inclusion of such conversations, without more, as vitiating an otherwise valid wiretap. The procedure testified to by the agents appears a reasonable method for complying with the order of the district court, in accord with the statutory mandate that the interception be conducted in such a way as to minimize the interception of communications not otherwise subject to interception under Title III. United States v. Cox, 462 F.2d 1293 (8th Cir. 1972), cert. denied, 417 U.S. 918, 94 S.Ct. 2623, 41 L.Ed.2d 223 (1974).
The district court specifically found that defendants Malloway and Baxter lacked actual knowledge of the use of interstate facilities in the gambling operation. This lack of specific knowledge is legally irrelevant. The words of § 1952 do not require specific knowledge of the use of interstate facilities and we agree with the decisions in other Circuits that such knowledge is not a prerequisite to criminal liability thereunder. See, e. g., United States v. Ro-selli, 432 F.2d 879 (9th Cir. 1970), cert. denied, 401 U.S. 924, 91 S.Ct. 883, 27 L.Ed.2d 828 (1971); United States v. Hanon, 428 F.2d 101 (8th Cir. 1970), cert. denied, 402 U.S. 952, 91 S.Ct. 1608, 29 L.Ed.2d 122 (1971); United States v. Miller, 379 F.2d 483 (7th Cir.), cert. denied, 389 U.S. 930, 88 S.Ct. 291, 19 L.Ed.2d 281 (1967).
Anderson individually challenges the district court’s handling of his evidentiary objection to certain of the intercepted conversations as hearsay. The trial court’s rulings on this matter shows a clear understanding of the law on the exception to the hearsay rule which applies to statements made by co-conspirators in furtherance of the conspiracy. See, e. g., United States v. Register, 496 F.2d 1072, 1078-1079 (5th Cir. 1974); United States v. Williamson, 482 F.2d 508, 513 (5th Cir. 1973). An examination of the record shows sufficient independent evidence of the existence of a conspiracy to which Anderson was a party to warrant the introduction of the hearsay conversations against him.
Affirmed.