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6921 SCCP Call Disconnected after 24-25 seconds


I just want to ask what are the possible reasons when a call originated from a 6921 using SCCP on CUCM 8.6 using H.323 gateway suddenly disconnects a call when a call is established after 24-25 seconds?

But when using SIP instead of SCCP in 6921, the call continiously flow

9 Replies 9

Gajanan Pande
Cisco Employee
Cisco Employee

Strange. What firmware versions ( SCCP & SIP ) the 6921's are running with ?


The SCCP firmware is 9-2-2-6 (the latest from 6921).

The SIP firmware from where it can call continously is

Thanks. Next question would be, are all SCCP phones facing same issue or it's just the 6921 SCCP phone ?

Could you post following debug for a failed call ?

debug voip ccapi inout

Please mention, calling & called number.

Also what is the gateway IOS version ?



I can't procure a copy of debug I made as I'am out of customer site  right now, but yes this happends on all sccp phones 6921, haven't tried  yet on the 7937 and 9951 since the site I was on only has 6921, will do  tommorow when I return.

The disconnect code I got with debug isdn q931 is 80AF btw

The gateway IOS is c3900e-universalk9-mz.SPA.151-2.T2.bin

Will provide additional info tom for the other phones (7937 and 9951). But what you think maybe the issue?

Just an update, All the IP Phones in our network suddenly disconnect after 25 seconds when the call is connected, before it was only the 6921 when configured with sccp. 6921 with SIP calls works before as well as 7937 (sccp) 9951 (sip). But now after adjusting the device pools for proper region assignment, all the ip phones registered with the following signalling protocol below disconnects after 24-25 seconds

6921 (sccp)

7937 (sccp)

9951 (sip)

IP Communicator (sccp,sip)

And the correct ios of voice gateway is "c2900-universalk9-mz.SPA.152-1.T1.bin".

Attached is the debug you requested for incomming and outgoing as well as the calling and called number

- debug isdn q931

- debug voip ccapi


Just checked the debugs, looks like the call manager is sending the disconnecct in both cases.

Is there actual audio on the call?

What is the call flow, is there a firewall in beteen.

We actually need the following debugs from the gateway:

1. deb h.225 asn1

2. deb h.245 asn1

And call manager traces set to detailed for a bad call, deb isdn and ccapi are not helpful in this case.

A wild guess would be h.225 tcp tear down may be because of a firewall or a timeout.

But with the debugs and traces requested we will have a better picture.



Karthik Sivaram


The call disconnects due to Cause=41 and the isdn disconnect is Cause i = 0x80A9 - Temporary failure.

You most likely have a network issue (firewalls or network issues over wan).

Is it possible for you to test with outbound fast start on the H323 gateway.

Please do attach...

Show run

Show gateway

debug h225 asn1

debug h245 asn1

debug h225 events

debug h245 events

Hope this helps!



Hi Kunal,

Just to answer your questions,

- There is a slight audio within the call, a bit choppy

- The call flow is thru Phone-->CUCM-->H.323 Gateway-->PSTN

- There is no Firewall in between the CUCM-->H.323 Gateway -->PSTN


Attached here is the two sets of debugs you requested, one is without faststart, one is with faststart enabled for outbound. All the calls I made here is outgoing


the h225 debugs show the following... 

pr 13 02:58:49.632: h323chan_chn_process_read_socket: fd=3 of type CONNECTED has data

Apr 13 02:58:49.632: h323chan_recvdata: No Data on fd=3


Apr 13 02:58:49.636: h323chan_chn_process_read_socket: fd=3 of type CONNECTED has data

Apr 13 02:58:49.636: h323chan_chn_process_read_socket: fd=2 of type CONNECTED has data

Hex representation of the SETUP TPKT received: 0802E0885A080280817E0022052580060008914A0005110011006DBAD7FA844B11E19C2DF34836968E3C10800100

h225ParseData: Q.931 RELEASE COMPLETE received on fd=2

Apr 13 02:58:49.636: h323chan_chn_process_read_socket: fd=3 of type CONNECTED has data

Apr 13 02:58:49.636: h323chan_recvdata: Connection lost fd=3

Apr 13 02:58:49.636: h323chan_close: TCP connection from fd=3 closed

> I see the tcp connection closing...

> I would recommend doing the following now...

1) from your ccapi debugs I see that incoming dial peer 0 is being used. .....

Calling Number=022148900,(Calling Name=)(TON=Unknown, NPI=Unknown, Screening=User, Passed, Presentation=Allowed),

Called Number=9760240(TON=Unknown, NPI=Unknown),

Calling Translated=FALSE, Subscriber Type Str=Unknown, FinalDestinationFlag=TRUE,

Incoming Dial-peer=0, Progress Indication=NULL(0), Calling IE Present=TRUE,

Please create a new incoming dial-peer as dial -peer 0 is the default dial peer.

2) bind the the interface on the gateway...using the command...

Router(config-if)# h323-gateway voip bind srcaddr ip_address

Hope this helps!



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