INTERGRATION OF THE IMS CORE AND THE IP PBX: A CASE STUDY

Abstract

The improvement of communications is not only create new and fantastic services, but also implies the migration and simplification of existing services. In today’s public networks, even NGN, there are neither products nor standardized solutions to provide corporate Private Branch Exchange (PBX)-like services. Currently, there are plenty of IP PBXs installed at corporate with rich set of IP Centrex features, e.g. call forwarding upon busy, call barring, etc. The example of such system is Asterisk, the most popular and open source IP PBX today, which is using SIP as session control protocol. While in the public side, IMS is approaching as the unique solution for the core of 3G and LTE networks. There is, therefore, a demand for integration and seamless interoperability between two domains, namely IMS at the core and IP PBX at the access/service layer. This short paper presents our initial experimental works for solving this problem. In our solution we propose to use Asterisk as the feature server on top of the Fokus’ OpenIMSCore to provide the IP Centrex services to IMS users. The proposed architecture will also use SER as IMS Gateway to mediate between non-IMS Asterisk and the IMS core components. The article also presents the test-bed that was implemented in order to prove the concepts and presents key considerations for the implementation.