[asterisk-users] ISP trunk session ID?

[Sergej Petrovsky]

Hi folks,

What I trying to do here is exactly this: http://www.asteriskdocs.org/en/2nd_Edition/asterisk-book-html-chunk/I_sect14_tt599.html

My provider given me a Huawei modem which have 2 phone jacks on it, but instead of using it I rather redirect my POTS number to my PBX. I ran into couple of bumps on the road but now it's "half-working". I extracted the SIP user, pass, server info from the modem and even managed to put my PBX into the same VLAN they use, on the exact same IP address like the modem but there is 1 problem:
It seems this modem also sends some session ID to the ISP's sip server, something what Asterisk doesn't by default. So if I do this:

1, Let the modem register at the sip service (the phone number can be called and ringing out)
2, Disconnect the modem
3, Let the PBX connect to the SIP server
4, PBX accepts the calls
5, About 5-10 minutes later it stops doing it, when I call the number it shows busy (beep, beep, beep), no matter if I restart Asterisk or not it won't work anymore just if I do the same trick again

I'm sure the remote SIP server breaks the voip channel or something, it does NOT drop me out tho, my PBX can register any time without problem but no packets will ever come forward me anymore. It's kind of hard to solve this from 1 side.

There must be some solution for this.

Please help!

Thank You,
Sergej