MGCP GW - Change Status i = 0xC2 - out-of-service

[Ayaz Khan]

Hello,

I'm getting the following output for incoming calls;

un  3 10:41:28.576 DST: ISDN Se0/0/0:23 Q931: RX <- SETUP pd = 8  callref = 0x0B5B
 Bearer Capability i = 0x8090A2
  Standard = CCITT
  Transfer Capability = Speech 
  Transfer Mode = Circuit
  Transfer Rate = 64 kbit/s
 Channel ID i = 0xA98383
  Exclusive, Channel 3
 Display i = 0xB1, 'KTSC'
 Calling Party Number i = 0x2081, '9222222222'
  Plan:Unknown, Type:National
 Called Party Number i = 0xA1, '9222222222'
  Plan:ISDN, Type:National
Jun  3 10:41:28.584 DST: ISDN Se0/0/0:23 Q931: TX -> RELEASE_COMP pd = 8  callref = 0x8B5B
 Cause i = 0x80A9 - Temporary failure
Jun  3 10:41:28.584 DST: ISDN Se0/0/0:23 Q931: TX -> SERVICE pd = 3  callref = 0x0000
 Change Status i = 0xC2 - out-of-service 
 Channel ID i = 0xA98383
  Exclusive, Channel 3
Jun  3 10:41:28.622 DST: ISDN Se0/0/0:23 Q931: RX <- SERVICE ACKNOWLEDGE pd = 3  callref = 0x8000
 Change Status i = 0xC2 - out-of-service 
 Channel ID i = 0xA98383
  Exclusive, Channel 3

We hear busy signal when calling in.  Not sure what "Change Status i = 0xC2 - out-of-service " , I engaged telco and they said it is something on our end, and the channels are busy.  They are not releasing.  I tried reseting the controller, restart MGCP from CUCM and GW.  Resetting the DSP.  Issue gets resolved for a while then comes back.

I don't see any channels being busy out through "show isdn services" command.

If anyone has any troubleshooting steps or has encountered this issue before, please share.

Thanks,

AK

[Manish Gogna · Accepted solution]

Hi AK,

Can you configure 'no mgcp fax t38 inhibit' on the router and check.

HTH

Manish

[Ayaz Khan]

Hey Manish,

'no mgcp fax t38 inhibit' resolved the issue.

Thanks for your help ! ! !

AK

[Suresh Hudda]

Hi Manish, +5 to you for pointing out to exact issue & solution for that. I am curious to know that how did you recognize the cause and why that command causing issue and why it has resolved after removing it. Can you please brief it little bit for me.

Suresh

[Manish Gogna]

Hi,

I have seen this error in the cases attached to the following bug

https://tools.cisco.com/bugsearch/bug/CSCsj24114/?reffering_site=dumpcr

Symptom:

Voice, Cisco Fax Relay and Fax Passthrough type of calls will fail when
mgcp fax t38 inhibit command is configured


Conditions:

This problem is noticed on Unified CM 6.0(1) and above.


Workaround:

When you disable T.38 fax relay, you also need to disable the default enabled
fxr-package, in addition to mgcp fax t38 inhibit, and reset the mgcp service.
Otherwise, you enable T.38 fax relay with default enabled fxr-package.

Further Problem Description:
Unified CM began to support T38 fax relay (CallAgent-controlled mode) based
on if fxr-package is enabled since 4.2 in Windows release and 6.0 in Linux
release.

The current design states if GW and Call Agent (CUCM) fail on the fax
protocol negotiation, all types of calls will be rejected including voice

HTH

Manish

[Suresh Hudda]

Thanks Manish for sharing the good info (+5) :-)

Suresh