Akbarian, Hamid.

This thesis proposes a design for a signaling gateway to address the issues of interoperability between H.323 and SIP. The two IP Telephony standards currently compete for the dominance of IP telephony protocols. We investigate and study these two protocols in terms of interoperability. The question central to this thesis is the issue of interoperability between H.323 and SIP. A signaling gateway model is proposed and designed to address and solve this issue. The proposed model includes Call Initialization, Call Setup and Control, Capability Exchange and Call Termination, which are the four fundamental features supported by H.323 and SIP for establishing calls. Furthermore, we design the four internal components, which are common to the four main functions mentioned above. These four components are type checking, decomposition, conversion and reformatting. In addition, we illustrate in six different cases the functionality of the proposed signaling gateway for establishing calls between H.323 and SIP. These six cases also demonstrate the conversion capability of the proposed signaling gateway during a call between H.323 and SIP endpoints.