Appeals by the defendants from three judgments (one as to each defendant) of the County Court, Nassau County (Harrington, J.), all rendered September 26, 1991, convicting each defendant of promoting gambling in the first degree (4 counts) and conspiracy in the fifth degree, upon a jury verdict, and imposing sentences.
*815Ordered that the judgments are modified, on the law, by reversing each defendant’s conviction for conspiracy in the fifth degree, vacating the sentence imposed thereon, and dismissing that count of the indictment; as so modified, the judgments are affirmed, and the matters are remitted to the County Court, Nassau County, for further proceedings pursuant to CPL 460.50 (5).
Contrary to the defendants’ contentions, Nassau County had geographic jurisdiction to prosecute them for promoting gambling in the first degree. The defendants, acting in concert with Bernard Rothman and certain other codefendants, participated in a bookmaking operation in Manhattan (hereinafter the Manhattan operation). On each of the dates that the defendants were charged with promoting gambling in the first degree, Rothman telephoned another bookmaking operation located in Nassau County (hereinafter the Meacham operation) to "hedge” or "lay off” a portion of the bets received by the Manhattan operation so as to limit the Manhattan operation’s overall risk and enhance its potential for profit.
CPL 20.40 provides, in part:
"A person may be convicted in an appropriate criminal court of a particular county, of an offense of which the criminal courts of this state have jurisdiction pursuant to section 20.20, committed either by his own conduct or by the conduct of another for which he is legally accountable pursuant to section 20.00 of the penal law, when:
"1. Conduct occurred within such county sufficient to establish:
"(a) An element of such offense”.
Rothman’s telephone conversations with the Meacham operation constituted conduct occurring in both New York and Nassau Counties (see, CPL 20.60 [1]; People v Botta, 100 AD2d 311, 315). That conduct was sufficient to establish an element of the crime of promoting gambling in the first degree which is defined, in relevant part, as follows:
"A person is guilty of promoting gambling in the first degree when he knowingly advances or profits from unlawful gambling activity by:
"1. Engaging in bookmaking to the extent that he receives or accepts in any one day more than five bets totaling more than five thousand dollars” (Penal Law § 225.10 [1]).
By hedging bets in Nassau County, Rothman knowingly advanced the Manhattan operation’s illegal gambling activity, one of the elements of the crimes charged (see, People v Botta, *816supra). Rothman’s conduct materially aided the Manhattan operation by decreasing its risk of loss and enhancing its profit potential (see, Penal Law § 225.00 [4]).
Pursuant to Penal Law § 20.00, the defendants were accomplices of Rothman and liable for his conduct because they aided and abetted him with the mental culpability required for the commission of the offense of promoting gambling in the first degree. Consequently, Nassau County had jurisdiction to prosecute the defendants based on Rothman’s conduct in that county (see, Matter of Silvestro v Kavanagh, 98 AD2d 833; see also, People v Guidice, 83 NY2d 630, 636).
The defendants’ conspiracy convictions must be reversed, however, as there was legally insufficient evidence to prove the particular conspiracy charged in the indictment. Viewing the evidence in a light most favorable to the prosecution (see, People v Contes, 60 NY2d 620), the single conspiracy alleged was not proven beyond a reasonable doubt. The People sought to prove that the defendants and others in the Manhattan operation conspired with individuals in the Meacham operation to commit the crime of promoting gambling in the first degree. While the evidence demonstrated the existence of a conspiracy among the participants in the Manhattan operation, that was not the conspiracy charged in the indictment.
" '[T]he gist of the offense [of conspiracy] remains [an] agreement, and it is therefore essential to determine what kind of agreement or understanding existed as to each defendant’ ” (see, People v Leisner, 73 NY2d 140, 151, quoting United States v Borelli, 336 F2d 376, 384, cert denied sub nom. Cinquegrano v United States, 379 US 960). In this case, there was no direct or circumstantial proof establishing beyond a reasonable doubt that the defendants entered into an agreement with the Meacham operation to promote gambling.
A conspirator must know of the agreement and intend to join the conspiracy (see, United States v Townsend, 924 F2d 1385, 1390). "The scope of [the defendant’s] agreement must be determined individually from what was proved as to him” (United States v Borelli, supra, at 385). There was ample evidence from which an agreement to join a conspiracy involving the Manhattan operation could be inferred, but evidence that the defendants agreed to join a separate conspiracy with the Meacham operation was lacking. There was no proof that Rothman told the defendants he was hedging bets with the Meacham operation. While the defendants were Rothman’s accomplices and therefore liable for the substantive offenses *817charged, "the charge of conspiracy requires proof not essential to the convictions on the substantive offenses—proof of an agreement” (Pereira v United States, 347 US 1, 11-12; United States v Townsend, supra, at 1393-1394). By acting in concert with Rothman, the defendants did not necessarily enter into a conspiracy with the Meacham operation.
Further, there was insufficient evidence that Rothman himself conspired with the Meacham operation. Rather, the evidence demonstrated that the Manhattan and Meacham operations—two separate illegal enterprises—engaged in certain business transactions initiated by Rothman. The fact that those transactions may have been of benefit to both operations does not mean that a conspiracy existed (see, United States v Townsend, supra, at 1392).
The defendants contend that all of the eavesdropping evidence should have been suppressed because the electronic devices installed by the detectives were capable of conversion from a pen register into an instrumentality which could intercept conversations. Thus, the defendants contend that they should have been treated as eavesdropping devices, and their use permitted only after a warrant based upon probable cause was obtained (see, People v Bialostok, 80 NY2d 738). Since a warrant based on probable cause was not secured, the defendants contend that the evidence should have been suppressed. However, we find that the failure of the police to obtain a warrant for the initial installation of the pen registers does not require suppression of the eavesdropping evidence. The detectives obtained information from the pen registers regarding telephone numbers called during the initial period of their investigation and used it in support of their application for the eavesdropping warrant. Even if that information had been excluded, other evidence supporting the application, including evidence acquired by surveillance and undercover officers actually placing bets by calling the subject numbers, provided probable cause for the issuance of the eavesdropping warrant.
We find that the sentences imposed were appropriate under the circumstances of this case (see, People v Suitte, 90 AD2d 80).
We have considered the defendants’ remaining contentions and find them to be without merit. Altman, Hart and Krausman, JJ., concur.