This specification defines extensions to the IPCablecom Network-based Call Signaling [NCS] protocol to support the following analog trunking for PBX interfaces on an embedded Voice-Over-IP client device in an IPCablecom environment: Ground-start lines; PBX one-way and two-way DTMF trunks.
ANSI/SCTE 165-11-2009 history
2009ANSI/SCTE 165-11-2009 IPCablecom 1.5 Part 11: Analog Trunking for PBX Specification