1.2 Softswitch

Based on the handled SIP functions criteria the softswitch combines the roles of three different elements:

• Back to Back User Agent – the core set of functions responsible for traffic control.
• Registrar server – location server supporting SIP registration functionality.
• Presence server – a network service which accepts, stores and distributes presence information.

These roles can be implemented on a single application instance or in multi-server deployment with dedicated instances serving a specific role. You can enable the roles per instance through its configuration file.