POTS Overlap Dialing Based On SIP Protocol

IP call is an important part of the business which next generation network provides, while the SIP protocol is an important communication protocol to the realization of VoIP applications. In SIP-based communications, AG(Access Gateway) device plays the role of SIP user agent, it is used to connect POTS and IP networks. DSLAM is the equipment involved in this paper, it is a kind of media gateway which connect the traditional telephone services and ISDN user terminal with the NGN network.The EU policy introduced competition among the telecommunication industry has caused various European countries to reform the telephone numbering scheme. As the open numbering scheme supporting NDC and local dialing, many countries' telecommunication sector and operators tend to use open numbering scheme. Thus, the media gateway, DSLAM connecting POTS and IP networks also need to be improved to meet the needs of open numbering scheme.In open numbering scheme, AG does not understand the significance of each number the users have dialed. This paper, we will describe SIP-based POTS overlap dialing. Unlike en-bloc dialing, DSLAM send an invite which contains all the digits to create and complete a call to AS, in an overlap dialing process DSLAM will send multi-invites to establish a connection.