Callmanager and Voice gateway

Unanswered Question
Jan 23rd, 2009

I need to disable all un-necessary protocols on my voice gateway. I have callmanager (6.11) and Cisco IOS voice gateway. I do not use sip or h323 to connect to any other voice gateway. Calls from phones only need to talk to callmanager and voice gateway and calls will go out from PRI on the voice gateway.

I also use SRST in case callmanager fails.

My understanding is that I only need sccp as the protocol for communication between callmanager, voice gateway and phones. So can I disable all H323 and SIP connections to my voice gateway? Callmanager always talk to voice gateway through SCCP. Is this correct? If callmanager fails, all phones will talk sccp to voice gateway. Is this correct? So is there any need for H323 connection in this scenario? If all my calls are going through PRI do I need to enable H323 or SIP connections to the voice gateway at all?

I know that for SRST we need H323. But this is only a service enabled on the router and no h323 connection to the voice gateway is needed. Is this correct?

Any link to any clear document?


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Overall Rating: 4 (1 ratings)
Chris Deren Fri, 01/23/2009 - 10:05

You typically configure the voice gw to either use MGCP, H323 or SIP, not SCCP. First determine which protocol you are using, the easiest way would be to identify the GW on the CallManager to find out if it's MGCP or H323 or SIP, then you can disable unnecessary config from it.

As to SRST you are correct it typically uses H323 so all the pertaining dial peers will need to stay for sure.



rdianat Fri, 01/23/2009 - 14:31

Hi Chris,

My voice gateway is H323 gateway. I do not use SIP anywhere. Is it true that either callmanager or Phones always connect to H323 voice gateway via SCCP?

Suppose callmanager fails, still phones will register with gateway via SCCP? is this correct?

If so is it safe to say that I can block all H323 connections from outside or inside to my voice gateway?


Chris Deren Fri, 01/23/2009 - 14:41

No, CallManager is your "protocol translator", a device can talk any of the supported protocols with CM. In your example the GW talks to CM via H323 and the phone talk to CM via SCCP (or they could use SIP), the phones do not talk directly with GW, the signaling always goes via CM under normal operation. If GW falls under SRST then the call-manager-fallback service supports SCCP signaling and phone talk SCCP with it, however the GW is still using H323 for PSTN connectivity. So, as you see you always use protocol transaltion in the mixture.

HTH, plese rate all useful posts!


Nicholas Matthews Fri, 01/23/2009 - 10:23

As Chris stated, you only have 3 options for PRI on gateways:

H323, SIP, MGCP. If you have a PRI, you're using one of them.

If you would like to disable the protocols you're not using:


no transport tcp

no transport udp


voice service voip


call service stop [forced]


MGCP is not open by default, it requires the use of the 'mgcp' command.



rdianat Fri, 01/23/2009 - 14:16

Hi nick,

I have disabled sip using


no transport tcp

no transport udp

but I still see SIP service is up and ready to accept connections. How can I completely disable this service?

gtwy#sh sip service

SIP Service is up

gtwy#sh tcp brief all

4741CC7C *.5061 *.* LISTEN

485BFAEC *.5060 *.* LISTEN


Nicholas Matthews Sun, 01/25/2009 - 20:54

When you enter the commands, make sure you have 'term mon' on. You're likely getting an error telling you that can't disable calls when you have active calls up.



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