Anton Yurchenko wrote:
I`ve hear people implementing ser as a proxy/registar for SIP and using asterisk as b2bua to gateway calls to PSTN
Yes, that's a possible solution. Check the autocreatepeers entry in sip.conf of Asterisk for a hint. Also, in bugs.digium.com there's a beta SIP channel I'm working on that could be helpful, but please remember it's a beta product.
You'll find more info and doumentation about Asterisk on http://www.voip-info.org
/Olle