Hi This harry thread , I now look forward to in the morning, wastes alot of space, but then so does spam. I have completely lost where I was on the thread about his problem, so harry I suggest you scrap what you have posted up until now, cause it makes no sense, also post only to serusers and openser, lets ignore asterisk for now. I am going to post my understanding of what you want, all those who have a clue please add, and lets see if we can solve Harry's problem, harry if we cannot, please accept that what you are doing is far too advanced for the mortal man/women (are there any women ?) on this list, and hence you must carve a path, where no one has gone before...either that or change what you are doing. So here goes..... 1 You have ser and asterisk running. Both have a public IP address, and asterisk runs on port 5050 and ser 5060 2. You want asterisk to handle INVITE and REGISTER via SER....my question is why do you want the UA to register in SER and asterisk 3. Or do you want SER to handle the REGISTER, INVITE and then when IM/presence is needed to use asterisk 4. Can you explain what you have till now, do you have UA registering with SER, and maiing calls to each other (without asterisk)..i.e normal calls IP <---> IP, with either or both of them behind a NAT...if not do this first, ignore the rest. 5. If 4 is correct, then have you got asterisk and ser connected together, i.e talking to each other Iqbal