A standard signalling protocol for Band III trunked systems

The derivation of a standard protocol, MPT 1327, for Band III trunked systems from an earlier code of practice, MPT 1317, is described. The protocol features include well-known forms of trunked system control, fast interaction on the 1200 bit/s FFSK control channels, numbering capacity for up to 1 000 000 identities on each of 32 000 systems on 1 000 channels, many different classes of call, roaming capabilities, etc. The protocol is suitable for all systems from the smallest single site ones to a system offering nationwide coverage. Although written for Band III the protocol could be applied on other bands or could use other forms of data modulation.