PRI q931 debug question

[shikamarunara]

I'm troublshooting a RightFax issue and am trying to determine the cause of a failed transmission. The context is;

- RightFax is attempting to send an outbound fax via H323 trunk to the gateway.

- Outbound fails with the following q931 information;

Dec 9 16:43:49.755: ISDN Se0/0/0:23 Q931: RX <- CALL_PROC pd = 8 callref = 0x803E

Channel ID i = 0xA98397

Exclusive, Channel 23

Dec 9 16:43:50.011: ISDN Se0/0/0:23 Q931: RX <- ALERTING pd = 8 callref = 0x803E

Progress Ind i = 0x8288 - In-band info or appropriate now available

Dec 9 16:44:02.020: ISDN Se0/0/0:23 Q931: TX -> DISCONNECT pd = 8 callref = 0x003E

Cause i = 0x81AF - Resource unavailable, unspecified

Dec 9 16:44:02.052: ISDN Se0/0/0:23 Q931: RX <- RELEASE pd = 8 callref = 0x803E

Dec 9 16:44:02.072: ISDN Se0/0/0:23 Q931: TX -> RELEASE_COMP pd = 8 callref = 0x003E

On the disconnect error "Resource unavailable, unspecified", it appears that it is happening during the transmission phase (TX). Does this mean that the failure is happening on the RightFax side, since it is initiating the outbound connection?

-Shikamaru

[#2]

Outbound faxes from the RightFax server going through the CCM cause the voice gateway to send error messages to the ISDN switch.

This is error is because of the requested channel or service is unavailable for an unknown reason. This might be a temporary problem. “Resource unavailable, unspecified" typically indicates a codec mismatch, and less typically a lack of DSP resources.

Make sure your CallManager regions relative to the fax server and this gateway are configured to use only g711.

[shikamarunara]

That's what the debug implies, but it's not the issue at all. The error was happening because of a gateway configuration issue. In this case, I needed to enable ecm for MGCP. I suspect that an error in the attempt to transmit with this syntax enabled results in this kind of q931 output.

-Shikamaru

[bryantlowe]

I;m currently troubleshooting a similar error. However, ECM is enabled and only calls from the rightfax servers to POTS lines are affected. I can send a fax to companies who have PRI lines.

I am assuming it has to be an issue with the ringback tone going back to H323 rightfax server.

[bryantlowe]

OK so I have a fix for my error. It turns out that i will receive this error " Cause i = 0x80AF - Resource unavailable, unspecified " when the destination fax doesn't pick up in time. My rightfax is setup with an H323 connection and doesn't have fast start enabled. So, the Service parameter " Media Exchange Timer " which was set to default at 12, was disconnecting the call after two rings. After we bumped up the timer, everything worked.