Improving quality in a distributed IP telephony system by the use of multiplexing techniques

Nowadays, many enterprises use Voice over Internet Protocol (VoIP) in their telephony systems. Companies with offices in different countries or geographical areas can build a central managed telephony system sharing the lines of their gateways in order to increase admission probability and to save costs on international calls. So it is convenient to introduce a system to ensure a minimum QoS (Quality of Service) for conferences, and one of these solutions is CAC (Call Admission Control). In this work we study the improvements in terms of admission probability and conversation quality (R-factor) which can be obtained when RTP multiplexing techniques are introduced, as in this scenario there will be multiple conferences with the same origin and destination offices. Simulations have been carried out in order to compare simple RTP and TCRTP (Tunneling Multiplexed Compressed RTP). The results show that these parameters can be improved while maintaining an acceptable quality for the conferences if multiplexing is used.