debug isdn q931 on gateway question

Unanswered Question
Jun 19th, 2008

Hi all. Im in the process of staging a new install and Im just trying to verify that digits are being sent over to my new gateway. I have it all configured and I have debug isdn q931 on, but Im not seeing the call trying to go through the router. Now, I do not have the PRI plugged in, I only have a T1 loop in to get a green CD light on the VWIC card. Im thinking I should be able to at least see the call trying to go out, even though it wont because of the loop back plug I have in it. Is this correct? I think I have everything set up correctly on the CUCM, the same as I have done it many times before, but Im just not seeing the digits come across to the gateway. I guess my question is if I dont have the PRI in place, would I see the digits come across to the gateway?

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Overall Rating: 4 (2 ratings)
mattcalderon Thu, 06/19/2008 - 06:43

I guess the most important question is if the gateway is mgcp or H323. If it is mgcp is the endpoint registered with the call manager? If it is not then the call manager would not attempt to send the call to an unregistered endpoint. If it is H323 I would say yes you should see the call if you have the correct dial peer configuration.

jjoseph01 Thu, 06/19/2008 - 07:31

Yeah, MGCP. Says "Registered" when I do a show ccm-manager. In CUCM, it says registered with the IP address of CUCM.

mattcalderon Thu, 06/19/2008 - 07:36

Did you verify your route patterns and route lists in ccm to make sure that when you make an outbound call you are indeed using that gateway?

jjoseph01 Thu, 06/19/2008 - 07:40

Yeah, its the only one I have setup now. I havent entered the other gateways yet.

jjoseph01 Thu, 06/19/2008 - 07:41

I can dial 911 and it starts to process the call, but I never see it on the gateway. I just didnt know if it was because of the PRI not being in place, and me just using a loopback.

mattcalderon Thu, 06/19/2008 - 07:42

I have never tried your exact scenario with a loopback plug on the PRI. I would think though you would see the call at least hit the GW. What is your out put of a "debug voip ccapi inout"

jjoseph01 Thu, 06/19/2008 - 07:48

No output at all. Just tried it. Just like with debug isdn q931. Just nothing.

mattcalderon Thu, 06/19/2008 - 07:52

That tells me that the call is never getting to the gateway then if you dont see anything on ccapi.

jjoseph01 Thu, 06/19/2008 - 07:59

Hmmmm. Ok, let me review, see what you think. I have a route pattern, 911, that says go to route list RL. RL points to route group RG, no special config in it. Route group has in "selected devices" S0/SU0/DS1-0... I click on that interface at the bottom and it takes me to S0/SU0/DS1-0 page, where it says registered with CUCM IP address. What else should I check?

mattcalderon Thu, 06/19/2008 - 08:03

have you verified partition and CSS? Run the DNA and see if the call goes where you think it does.

The config does sound right though.

mattcalderon Thu, 06/19/2008 - 08:10

Its the Dialed number analyzer. I don't know what version of CCM you have, but it would be in the plug ins as an application to download. This takes what is in your database and uses those configurations to simulate a call and where it would end up.

Here is a little something on it but you may have to find something more specific for your version.

jjoseph01 Thu, 06/19/2008 - 08:29

I have 6.1.1 . Just went and looked for it on the plugins page. Didnt see it. Going to look at the link you sent.

jjoseph01 Thu, 06/19/2008 - 08:41

ok, thanks. going to eat some lunch. will check this when i get back.

shawilson Thu, 06/19/2008 - 09:08


I have run into this situation many times before, and you will never see any call information on the mgcp gateway until you have complete l2 and l3 isdn backhaul to the UCM. From your IOS gateway, it will show as registered, but from the UCM, it will show as unregistered. Once you have the PRI connected, the status on the UCM will change to registered and you will be able to see isdn l2 (q921) and l3 (q931) call information.

jjoseph01 Thu, 06/19/2008 - 09:47

ok, back now. Yeah, I have a loopback on it and it says registered. GOing to look for DNA now.

jjoseph01 Thu, 06/19/2008 - 09:55

Sorry guys, still looking for this. Any idea in particular in Serviceability where it is?

jjoseph01 Thu, 06/19/2008 - 10:02

Ok, found that it was not activated in service activation. I activated it, now looking for it to download.

jjoseph01 Thu, 06/19/2008 - 10:07

ok, found it and going through it now. I think it basically is saying what it uses for that route pattern (911) and uses the RG, RL, etc that I stated earlier. Still looking through it.

jjoseph01 Thu, 06/19/2008 - 10:14
jjoseph01 Thu, 06/19/2008 - 10:37

Maybe it just doesnt if the PRI isnt connected, and a loopback doesnt work for this????? Im not sure, as I have never really tried this in a lab before. I just thought Id like to test it out and so I tried it. Not KNOWING if it will work or not.

jjoseph01 Thu, 06/19/2008 - 11:15

Im going to go ahead and rate this, even though Im not sure why it doesnt show up. I appreciate the help Matt. I learned about the DNA, so this has been very helpful to me. I think its configured correctly, Im just not sure why it doesnt show at the gateway. Both see each other as registered, call flow seems to go out that PRI line (looped back) according to DNA. I wonder if the call must go "through" the gateway instead of "to" the gateway before it shows??? Not sure, but Im guessing that may be it. Thu, 06/19/2008 - 11:58


I have seen this problem before where no voip debug comes through, is the Route List registered? try resetting it.

Did you do a show isdn status? It must say "Multiple FRAME Established". I highly doubt this is going to work without a PRI turned up. Simply looping the interface will not be enough.

Otherwise, try "debug isdn q921" and see if you are getting SABME messages in the debugs. If you see it sending in one direction, then simply looping the interface will not work.

iptuser55 Fri, 06/20/2008 - 02:16

I also have an issue same as this in that the DNA is routing the call but no L3 on the debugs

iptuser55 Fri, 06/20/2008 - 02:17

I also have an issue same as this in that the DNA is routing the call but no L3 on the debugs


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