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Outbound H.323 Calls dropping after 180 secs



I know what you're's one of the T3xx timers, and it is. The problem is, how to stop the timer expiring and dropping calls....hmmmm

This is the deal: We've got an ISDN30 line into an H.323 GW which talks back to CUCM 7.

Incoming calls work fine, outgoing calls to mobiles/cells, work fine, but with calls to landlines, the call always drops after 180 seconds.

Cisco TAC are working on this at the moment, and have been all week, but to no avail.

Config of interest...

interface FastEthernet0/0

ip address

speed 100


h323-gateway voip interface


interface Serial0/0:15

no ip address

encapsulation hdlc

no logging event link-status

isdn switch-type primary-net5

isdn incoming-voice voice

isdn sending-complete

no cdp enable

dial-peer voice 1 pots
description Outbound TO PSTN
destination-pattern .T
progress_ind alert enable 8
port 0/0:15
forward-digits all
dial-peer voice 2 pots
description Inbound Dialpeer
incoming called-number .T
dial-peer voice 101 voip
description TO CUCM
destination-pattern 2...
progress_ind setup enable 3
session target ipv4:
dtmf-relay h245-alphanumeric
codec g711ulaw
no vad
voice-port 0/0:15
cptone GB
controller E1 0/0
pri-group timeslots 1-12,16
I can see on the display of the phone, that when the call connects, the phone still thinks the called number is still ringing (Still shows "Ring out")
There's clearly a message missing somewhere, but I just can't but my finger on it.
I added isdn sending-complete at the request of TAC, and changed the timers (no reflected in above config), but no joy.
I can see how the timers would increase the length of time before a dropped call happens, but really, I'm looking to find the root cause of the problem.
Always get this: "Cause i = 0x80E6 - Recovery on timer expiry"
Would welcome any comments, nudges in the right direction, or even the answer
Many thanks
1 Reply 1

Cisco Employee
Cisco Employee

From your description, it seems for the outgoing landline calls, the

GW is not receiving q931 CONNECT so T301 pops.

Did u try   isdn timer T301 xx   CLI  under serial/d-chan interface?

If u run debug isdn q931, it will confirm whether we are rec. CONNECT
back or it stays in Alerting/Progress.

There is one other possibility which is that CONNECT from PRI leg is

not being propagated to the voip/h323 leg.

But start with q931 debug.

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