Session Initiation Protocol (SIP) Is an advanced voice connectivity product, with the best in class IP solution. It replaces Traditional PSTN lines with a single physical link that can support up to 1500 simultaneous calls. Scaling up and down call capacity on SIP trunk is very easy, quick and can be done in multiple of 10 channels. It reduces cost of multiple lines, maintenance as well as hardware requirement for multiple PRI ports. Network service availability of 99.5% with MTTR of 4 hrs. Scalable on a single link with 20 to 1500 simultaneous calls with no dependency on physical cards Service delivered through Class 5 NGN switches. Flexible DID range to meet requirements