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Cause Codes - Mapping between H323 and SIP

Ben Morgan

Hey all,

Im troubleshooting an outbound dialer issue at the moment. I have an Outboudn Dialer server connect to CUCM 8.6 via a SIP Trunk. The CUCM also has a h323 gateway going to the ISR which has an ISDN 30 service.

Outbound-Dialer -> SIP -> CUCM -> H323 -> ISR -> ISDN

Now the problem is cause code mapping. I need to have the IOS gateway and/or CUCM pass the correct disconnect cause codes through to the Outbound dialer.  When I call a phone that is currently Busy, I receive an case code of 0x8491 - User Busy, so this cause code is displaying correctly. However, tracing SIP to the outbound dialer I see a disconnect code of 487 - Cancelled or BYE. This should be showing cause code 486 - User Busy....

I know the outboudn dialler signals CUCM to make the call outbound, upon successful call setup with the destination phone, CUCM then strikes up a call to the Agent then connects the two legs together.

SO Im trying to figure out where the cause codes are getting mixed up, can only be in two places.. either the IOS gateway is not passing the correct codes to CUCM, I dont see this to be the case though as h323 is closely related to ISDN signalling etc. The second place is on CUCM.

Does anyone have an outbound dialler in operation and if so do the cause codes map correctly.

Is there a way to map H323 to SIP Cause codes within CUCM? or to atleast enable the cause codes to be transparently passed through?

Any help is appreciated.



2 Replies 2


That is strange because the default sip to pstn mapping maps cause code 17 to 486..

You can change your the mapping like this..

conf t


set pstn-cause 17 sip-status 486

Give it a go and test it...

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Thanks for the reponse. That didnt work.

I went through the SDI traces last night. Heres the breakdown.

Outbound dialer send invite to CUCM


CUCM send H225 Setup to gateway.

CUCM receives H225 USER BUSY (17)

CUCM sends Session in Progress 183 to OUtbound Dialer

30seconds pass..

CUCM sends CANCEL to outboudn Dialer

Outbound dialer Acknowledges

I done some reading.. Im not why the CUCM is sending a 183 reply to the Outbound dialer, but I pretty sure this telling the outbound dialer to play ringback to the agent's phone, so its like the SIP session is up in early media format, but then after the SIP timers expire, the call is cancel, thus CUCM is send 487 CANCEL to the outbound dialer.

I will try to disable Early Media in the SIP Profile assigned to the Trunk. See how that goes.. but if you have any other ideas, please let me know.



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