VOIP call drop after 30mins frequently

Unanswered Question
Aug 17th, 2010
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Hi all,

Could anyone know my problem in voip call as follow ?

HK PSTN/local extension---HK PBX---HK VG----HK CE----HK PE----MPLS Network Cloud—US PE---US CE---US VG---US PBX—US PSTN/local extension

When customer called to US from HK via voip, the call sometimes will be dropped around 30 mins. Please refer to the below call history for your reference.

The service provider have check the the MPLS circuit is fine.



3EF5 : 3 361780ms.1 +2750 pid:0 Answer 82000 active
dur 00:20:01 tx:2297/44343 rx:29949/1197882
IP SRTP: off rtt:211ms pl:1197050/2010ms
/5/0 delay:80/80/100ms g729r8
media inactive detected:n media contrl rcvd:n/a timestamp:n/a
3EF5 : 4 361780ms.2 +2750 pid:11 Originate 84918886692803 active
dur 00:20:01 tx:29949/1437474 rx:2297/44343
Tele 0/0/1 (4) [0/0/1] tx:1201680/44910/0ms g729r8 noise:-69 acom:54  i/0:-69/-15 dBm


Is there any issue will make the call drop ?

Thanks  a lot

Leung Che Man

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paolo bevilacqua Tue, 08/17/2010 - 02:28
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Are you using sip or h.323 ?

paolo bevilacqua Tue, 08/17/2010 - 02:44
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Before they leave for the day, enable "debug cch323 all". Log to buffer or a server.

Have then place a call and the following day, check for revealing events.

Please do not use attachments for small files.

paolo bevilacqua Tue, 08/17/2010 - 12:51
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Please take the trace in a way sthe long lasting calls is the only one.

I do not believe you need to take debug isdn q931 because most likely the problem is in the routers, you can take it anyway if you want.

Steven Holl Tue, 08/17/2010 - 07:18
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In my opinion, there are better debugs to shed light on this than 'debug cch323 all.'  Chances are, the call is getting dropped due to one of three reasons:

a) The PBX is sending a disconnect.

b) There is a network issue causing the H225 or H245 TCP connections to timeout/drop

c) A media inactivity timer is popping.

First, make sure there isn't a media inactivity timer configured on the gateway under the 'gateway' section in the config.

Second, it may shed some light on root cause if you can see if a counter increments on 'sh h323 gateway cause' after the issue occurs.  That will at least let you know the q.850 cause code for the drop, and point you in a certain direction.

Otherwise, or to be conclusive, run these debugs on both of the VGs:

debug h225 asn1

debug h245 asn1

debug ip tcp trans

debug isdn q931 <--- Assuming the VGs are running PRIs.  Use debug vpm sig if these are CAS/analog circuits.

debug voip ccapi inout

Collect debugs in the following manner:

Router(config)# service sequence
Router(config)# service timestamps debug datetime msec
Router(config)# logging buffered 10000000 7
Router(config)# no logging con
Router(config)# no logging mon
Router(config)# voice iec syslog

Router# term len 0

Router# sh logg

Note calling/called number for the call with the issue.

-Steve Holl


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