Remote host can't match request CANCEL


From time to time there are incoming external calls (via a SIP trunk from a provider) that we can’t pick up. When the user picks up his phone the following message is logged :

From the end user’s point of view : when he effectively picks up his phone, it hangs up immediately. The call is not picked up, the other target phones keep on ringing.

And this lasts until the remote caller decides to hang up the line on his side.

This happens completely randomly.

No problem at all with internal calls, and with outgoing external calls.

A snip of extensions.conf for an incoming call :

exten => 0133841699,1,NoOp(Incoming Call for Toto on 01 33 84 16 99) exten => 0133841699,2,Set(CALLERID(name)=Call for Toto) exten => 0133841699,3,Dial(${GROUPE1},12,rtT)

A snip of sip.conf (internal account) :

[toto] type=friend context=default defaultuser=toto secret=toto host=dynamic callerid=Toto <100> disallow=all allow=alaw callgroup=1 pickupgroup=1 directmedia=no qualify=yes

A snip of sip.conf (SIP provider) :

[provider-output] disallow=all allow=alaw type=friend insecure=port,invite fromuser=0133841699 directmedia=no qualify=yes

I can’t figure out what could be wrong, if you could please give some help…

  • Asterisk
  • Debian 6.0 (Squeeze)
  • Internal IP phones : Cisco SPA504G, Linksys SPA942, Linksys SPA922

I don’t think the phones are the root of the problem, it would rather be Asterisk… Or possibly the SIP provider ?

Thanks in advance.