This Recommendation specifies a signalling protocol for the purpose of call control at the QB, SB, TB, and co-incident SB/TB reference points within, between, and at the access to Broadband Private Integrated Services Networks and within, between, and at the access to Broadband Integrated Services Digital Networks. The protocol operates between two adjacent call control entities. The protocol is applicable to a terminal or network node in a separated call and bearer (connection) control environment for the support of calls having none, a single bearer or multiple bearers. The protocol is applicable to a two-party call. The protocol also provides forward compatibility to the extent that an implementation can also operate within a multi-party call with other implementations that use additional capabilities, provided the implementation is deployed where it does not need to be aware of more than two parties.