The ACU SIP-LMR Channel Bank provides a seamless interface between radios and an IP- based network using the SIP protocol. This brings to existing SIP networks all of the features inherent in a radio system, including the ability to wirelessly reach otherwise inaccessible areas. For example, the ACU SIP-LMR can be used with an LMR system to extend the SIP Network into areas of rugged terrain, across bodies of water, or into tunnels. Radio networks can now benefit from all of the features available with SIP. These include interoperable communications among disparate radio systems that is as easy as creating a typical PBX conference call and also other PBX features such as Call Logging, Call Forwarding, and Call Recording.