OpenSIPS is an Open Source SIP proxy/server for voice, video, IM, presence and any other SIP extensions.

OpenSIPS is a multi-functional, multi-purpose signaling SIP server used by carriers, telecoms or ITSPs for solutions like Class 4/5 Residential Platforms, Trunking / Wholesale, Enterprise / Virtual PBX Solutions, Session Border Controllers, Application Servers, Front-End Load Balancers, IMS Platforms, Call Centers, and many others.

OpenSIPS is recommended for any kind of SIP scenario / service by:

• the high throughput - tens of thousands of CPS, millions of ‏simultaneous calls (see official tests)
• the flexibility of routing and integration - routing script for implementing custom routing logics, several interfacing APIs
• the effective application building - more than 120 modules to provide features, for SIP handling, for backend operations, for integration, for routing logics
• integration capabilities with non-SIP protocols or other software / components which are typically part of complex SIP platforms.