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fxo port of Voice Gateway configured as mgcp on the CUCM experienced lockout/stucked even there was no call

Level 2
Level 2

Hi Guys,

We encountered an issue wherein we cannot call using the FXO Ports(Analog lines) which are registered to the CUCM as MGCP. Upon checking, these FXO Ports were currently in used, however we found out that there was really no calls which means the FXO Ports seem locked/stucked.

I know that this issue regarding fxo ports is very usual, however is there anything to prevent this to happen again?  And what triggers the lockout/stucked of fxo ports?

Thank you.

7 Replies 7

Manish Gogna
Cisco Employee
Cisco Employee

You can ensure that the router is running the minimum recommended or a higher IOS version as per the cucm compatibility guide.

If the issue is still experienced then you may need either "debug mgcp packets" or detailed callmanager services traces for a test call to see if there is any signaling issue or a bug.


Hi Manish,

Do you think it has something to do with the IOS version of the VG? Current IOS Version is c2900-universalk9-mz.SPA.152-4.M2.bin while CUCM is on version 8.6.

I have read a document regarding supervisory disconnect configuration but i think this is just for the h323 voice gateway.

Do you have any idea of a bug related to this issue and current ios? Already checked it on the release note however we did not see anything related.

Thank you

Th IOS version looks good. You can reload the gateway and then make a few test calls after enabling the debugs to observe if the fxo ports gets blocked immediately. Basically it needs to be checked for which calls the port is not being released.


Actually the thing that we usually do when encountering this kind of issue is that we will shutdown and no shut the port. or unplugged and plugged again the cable physically.

However the customer needs to know if how can we prevent this in happening again. Appreciate if you still have any recommendation or information regarding this kind of issue with the FXO ports.

Thanks again Manish.


Can you post your configuration in here.

-Kevin Monteiro


Please post your config? Also, did you try to use ground start?

Hi Mohammed,

Kindly see the attached configuration. This VG is registered to CUCM via MGCP.