ser or SIP Express Router is a very fast and flexible SIP (RFC3261)
proxy server. Written entirely in C, ser can handle thousands calls
per second even on low-budget hardware. C Shell like scripting language
provides full control over the server's behaviour. It's modular
architecture allows only required functionality to be loaded.
Currently the following modules are available: Digest Authentication,
CPL scripts, Instant Messaging, MySQL support, Presence Agent, Radius
Authentication, Record Routing, SMS Gateway, Jabber Gateway, Transaction
Module, Registrar and User Location.


WWW: http://www.iptel.org/ser/