Phones going to voicemail after gateway reboot

Unanswered Question
Jan 20th, 2010

We have CUCM 7.0 in our main site and branch gateways configured via MGCP.

I have a couple of general questions, sorry for the basic nature:

Recently a branch gateway was rebooted, after everything was back on line, the branch phones went immidiately to voicemail when dialing from the main site.

All network communication was back up and the gateway showed it was registered in call manager.

Could this mean the phones did not register properly?

Sometimes after a power cycle, it looks as though the phones register in the site gateway, the phones get their ip address from a dhcp pool on the site gateway. Do the phones also register with the local gateway when configured via MGCP, or in the main site call manager?

Recently there was a problem that was discovered by a determiniation that the call signaling was not getting to the local gateway. Would this be sccp signaling locally and I should be able to troubleshoot the signaling with a debug correct?

I have this problem too.
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jeff.heckart Thu, 01/21/2010 - 08:32

Is your voice gateway also handling the WAN?  It sounds like the IP phones are registering with SRST to the voice gateway.  If this is the case, then the branch IP phones would show up in CUCM as unregistered, and you're call-forward unregistered setting is probably set to go to VM.

If you look in CUCM after the gateway reboot, are your branch phones listed as registered?

wilson_1234_2 Thu, 01/21/2010 - 13:18

You are correct,

The problem was the phone was an IP Phone and registered to a call manager cluster that no longer exists.

Thanks.

But my other basic questions, sorry:

Our branches are using MGCP from branch to Hub site Call Manager cluster, they are also configured for SRST.

Each branch has a DHCP scope that the phones use to get an IP address and option 150 is pointing to the CM cluster in the main branch.

Normally the phones would be registered to the device defined in option 150, but when they loose connectivity to call manager, do they immidiately attempt to register with the local SRST gateway?

Also, when the phones get their config file, this is what should tell them to register with the SRST gatewayway if they cannot find call manager, is this correct?

If so, where does the config file get the information?

Does call manager create the config file based upon how the gateway configuration is in call manager?

I am thinking that when I see the phones register in the local gateway, the only time that would happen is if the branch is going into SRST mode, is this correct?

And,

Recently there was a problem at a branch and it was discovered that the call signaling was not getting to the local gateway.

Do the local branch phones always send signaling to the local gateway, or is this an SRST function?

Would the signalling be sccp and can be seen with debugs?

Hi,

Normally the phones would be registered to the device defined in option 150, but when they loose connectivity to call manager, do they immidiately attempt to register with the local SRST gateway?

Option 150 is your TFTP server which typically runs on the publisher (depending on the environment) and the phones get their config file from TFTP server. Yes, phones will immidiately try to register to SRST gateway if they lose connectivity to CUCM.

Also, when the phones get their config file, this is what should tell them to register with the SRST gatewayway if they cannot find call manager, is this correct? Yes, this is correct.

If so, where does the config file get the information? The config file gets the information from you. When you configure a phone, the config file for that phone is store on the TFTP server.

Does call manager create the config file based upon how the gateway configuration is in call manager? I am not quite sure on this one. I know there a config file store on TFTP server for each phone. Not sure about gateways.

I am thinking that when I see the phones register in the local gateway, the only time that would happen is if the branch is going into SRST mode, is this correct? Yes, Phones will register to SRST gateway when they can't connect to CUCM.

And,

Recently there was a problem at a branch and it was discovered that the call signaling was not getting to the local gateway.

Do the local branch phones always send signaling to the local gateway, or is this an SRST function? No, not always. Only when it needs to register to register to the gateway.

Would the signalling be sccp and can be seen with debugs? Yes, SCCP would be the control signaling for phones.

Hope that helps !!!

D.

wilson_1234_2 Thu, 01/21/2010 - 16:32

Yes,

Very helpful. Thank you.

On the call signaling, is the signaling traffic from the branch phone to Call Manager, or does the signaling happen from branch phone to branch gateway?

Also, the signaling would be setting up the call correct, then the signaling is complete and the communication is done via RTP stream?

Is the signaling for setting up the call considered MGCP, or h323 or SIP?

On the call signaling, is the signaling traffic from the branch phone to Call Manager, or does the signaling happen from branch phone to branch gateway?

The signaling traffic is between phone and CallManager.

Also, the signaling would be setting up the call correct, then the signaling is complete and the communication is done via RTP stream? Correct, CallManager is involved during call set up only.

Is the signaling for setting up the call considered MGCP, or h323 or SIP? No, these are control signal for gateways. For phone is SCCP.

Hope that helps !!!

D.

wilson_1234_2 Fri, 01/22/2010 - 07:59

Yes,

Helps very much.

So the signalling traffic is sccp from phone to Call Manager correct?

we recently had another issue at one of the branches where no one could make any call in or out to this branch.

Any attempt in would return a fast bust and any outbound attemp would return a fast busy.

The problem and solution from the phone guys was:

"The route list for that branch was stuck and had to be reset."

When I asked how they knew this was the problem, the answer was:

"The call control signaling was not reaching the gateway."

He had to be talking about the MGCP signaling from Call Manager to the gateway correct?

Hi,

So the signalling traffic is sccp from phone to Call Manager correct?

That is correct.

He had to be talking about the MGCP signaling from Call Manager to the gateway correct?

Yes, correct. There 3 different control signalings for gateways that I know of. MGCP, H.323 and SIP. Looks like people are moving away from MGCP as it's not as reliable as others and SIP is getting more popular as it is cheaper and the technology has improved a lot.

Hope that helps !!

Danny

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