sip_session: handle exception in connect() properly

darcs-hash:20090323143127-b2873-da19a671190baf365c07f37d1eb19dd298d4de6a
update sip_session to use configuration system

darcs-hash:20090323143420-b2873-f001628041a212fe102b76cbf2d2d3e50921e31a