MGCP/FXO Incoming call issue

[VoIP-Tech]

Hi all,

Dealing with an issue with MGCP FXO line on incoming calls does not provide any signaling trace on the gateway, nor the state of the line changes from 'idle'. When an outbound call is forced over the same line, it completes without any issue. Telco doesn't support caller-ID hence no way of confirming whether the number in question is the actual line (unfortunately). Technicians tested the line at demark that passed both ways (incoming/outgoing) without issue. 

Standard items have been done with no success, including reboot, rests, port reconfig etc.

There is not much of a complexity on an FXO line, it's a pair of wires, so if an outbound call completes ok indicates no connectivity issues with the line. How a connected line that completes an outbound call ok, won't provide any signal on inbound call is quite odd. 

Thoughts?? welcome.

TIA

[John Steele]

Have you considered it's an IOS issue?  Perhaps you should consider upgrade/downgrade.  Additionally, being MGCP i'd consider rebooting the CUCM cluster; you never know.

[Nithin Eluvathingal]

Are you saying that the logs don't show incoming calls, but the call details are visible when making calls? Also, it's a bit confusing that you mentioned the port shows as idle when an incoming call reaches it.

Could you share your CUCM MGCP configurations and the gateway configurations, if you don't mind?

Additionally, is there a specific reason you opted for MGCP for the FXO?

[VoIP-Tech]

I don't think IOS is coming into play here as the other lines on the same card are working just fine. Furthermore when an outbound call is established over that port, an incoming call placed to the target number from PSTN gets a busy signal, meaning the same line is siezed for the established call.

Port configurations on CUCM and gateway are exactly the same for the line with the issue compared to other lines, hence no missing config between a working and non-working line.

Upon incoming call, the line stays idle as if no voltage is sent. Can a port act weird like this to just not respond to an incoming call while successfully complete a call place outbound on it?

If the line or wires had an issue, I'd expect it won't complete an outbound call either but that's not the case.

Selecting MGCP for FXO is global and other lines works perfectly fine on the same gateway same config so it's a moot item.

Rebooting the entire CUCM cluster for a single port issue on one of the many gateways is an overkill and I don't think it will bring fruitful results. 

[Roger Kallberg]

Have you tried with swapping with another analog circuit that you know works to rule out issues with the port itself? If the problem follows the cable you’ll know it’s an issue with the specific circuit and if it stays at the FXO port you’ll know it’s an issue with the port itself.

[VoIP-Tech]

Roger, that's exactly what I've planned for, but could take a while. Thanks for chiming in.