Asterisk and SER

Will Asterisk work alone as a SIP Express Router? Is anyone doing this? Or do I need to add a SIP Express Router/OPENSER alongside Asterisk to get both Media Gateway and SIP Express Routing?

The configuration will be used as an ITSP/VoIP service provider.

Thanks

John

Asterisk is a B2BUA (back-to-back user agent) and registrar. It is not a SIP router. It also has voice mail, etc. If you need SIP nat functionality or routing, Asterisk will not do it alone. You can try OpenSER.