Hello, I have more feedback regarding the question I posted yesterday (Call forward & SER as SIP router) . pstn->SER->asterisk (call forward)->SER->Pstn fails when the far end picks the phone up. Error showed in asterisk is Got SIP response 481 "Invalid CSeq Number" back from XXX.XX.XX.XX (SER). Trying the same call with pstn->SER->asterisk (call forward) -> asterisk-> Pstn works fine! Does anybody implemented the scenery explained above? Could anybody give me a clue? Regards, Victor. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20050809/516029b1/attachment.htm