If the Branch Gateway contains an MM710 T1/E1 media module, it is advisable to define the MM710 as the primary synchronization source for the Branch Gateway. In so doing, clock synchronization signals from the Central Office (CO) are used by the MM710 to synchronize all operations of the Branch Gateway. ISDN BRI trunks Media Modules (MM721, MM722) can also use signals from the Central Office, to synchronize all operations of the Branch Gateway.