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ringback issue


Have a issue where calls from remote site with a Ericson PBX with E&M trunk to h323 gateway, then VoIP dial-peer over to central h323 gateway. Have E&M trunk there into avaya PBX. Avaya PBX has 2 PRIs into another router with MGCP and call manager associations.

When a user from remote site calls an IP phone at central site, they hear 1 short ring and then silence until someone picks up the call. The user can call an phone off the Avaya PBX and get ringback as normal. It's just with IP phones. Occassionally, but rarely the user heres normal ringback when calling IP phones. The IP Phone rings normally and the people can have a conversation just fine. Ringback on remote end is only problem.

We have tried progress_ind alert enable 8, and progress_ind setup enable 3, and global command call voice send-recv (if i recall right) without any change.

Anyone have any other ideas? What would I look for in debugs (voice ccapi inout, vpm sig) to see if ringback is being sent? How about in CCM traces?

Any chance of this being a MGCP type issue, and changing to H323 might have difference?



Re: ringback issue

In relation to the problem you are seeing with the FXO port, I suspect this is due to the ringing duration coming from your PABX being to short to trigger the FXO port. Since the PABX is giving a ring voltage between 90 and 120 volts, this is more than enough to trigger the FXO port.

I think the duration of the ring is too short, so the FXO port is ignoring it (possibly thinking it is just a voltage spike). A way to test this is to plug a very basic telephone handset into the PABX port, and ring the number. Try and determine how long the phone rings for - confirm if you get a very short burst of ring, then silence, then another burst of ringing. If this is the case, then you will need to see if the PABX can be programmed to provide a different ring cadence, so the actual ring duration is extended, thereby allowing the FXO port to detect it properly. We have seen this issue before and the ring duration is generally the problem.

Also check for the polarity of the PBX output and FXO module and voltage output too.


Re: ringback issue

I'm not sure if this will help but I noticed on my MGCP gateways on the CCM profile at the bottom there is a note "****may be required to force ringback from some PBXs", this is indicated against the field "Setup non-ISDN Progress Indicator IE Enable****". You might check to see if you have this checked.

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