A telecommunication network serves first subscribers by a first Centrex telephone exchange (CTX) via a first telecommunication switch. A first signal is received at the first switch from the first CTX which indicates that call origination services are to be provided directly by a second public network switch for a first subscriber. The second switch is disposed at a hierarchical level above the first switch. A second signal is received at the second switch from the first CTX indicative of the identity of the first subscriber. A record is located in a database coupled to the second switch based on the identification of the first subscriber. A group affiliation parameter stored in said record is identified; the group affiliation parameter defines one organization of which the first subscriber is a member. The second switch transmits a call setup message to a third switch associated with the second (called) subscriber; the call setup message includes the group affiliation parameter so that the first subscriber's membership in the one organization can be used in further call processing.