Calls disconnecting after 2 rings sometimes

Hi,

I have asterisk 1.2.7.1 with tdm channels. it is working fine.i have weird problem. sometimes my extensions ringing twice and goes to voicemail. it happens sometimes only… i am not able to find the issues… i shall be thankfull, if any one help to fix fhe same.

Thanks in advance

post your CLI output? what happens on the * console when this occurs?
also post the relevant dialplan section?

Thsi is my dial plan

exten => 238,1,Dial(SIP/238,20,rtT)
exten => 238,2,voiceMail(238@voicemail)
exten => 238,3,PlayBack(vm-goodbye)
exten => 238,4,Hangup()

for the extension,which i was facing the issues…

As for cli it gives the normal, which goes to voicemailmain…

that SHOULD ring for 20 seconds, not 3. The only reason it would cut off early is because of a problem with the SIP destnation, either the phone rejected the call or was not reachable. Try enabling qualify=yes for the phone, that may help…

also if the phone is on the same network as *, make sure its nat traversal is off and it’s not using STUN…

lastly if there is really nothing out of the ordinary on the CLI (post it anyway?) try a sip debug…