Media Termination points and media paths with CUCM

[Joe Carey]

Hi all,

I could really use some help regarding this topic. Please allow me to explain the situation.

Ok we have some endpoints that are not Cisco but cisco have developed cop files for CUCM and they are seen as a cisco device and register the same as any other phone. This isn't anything to do with the problem, but I want to make this clear. These are actually dealerboards for trading and register cisco lines the same as any other cisco telephone.

Ok so here is the story;

We have a CUCM cluster in London and a local gateway for local PSTN breakout. There are endpoints that are in Dubai and the register to the CUCM cluster in London. Dubai have their own MGCP gateway for local breakout to PSTN.

Here is the problem;

When a Dubai endpoint makes a call to a PSTN number in dubain there RTP is send from the endpoint, back to the London CUCM, the London CUCM then points the RTP at the gateway in Dubai. This is using a lot of bandwidth and I am not clear on how to change this so the endpoints send media directly to their MGCP gatway.

In my lab I have sent up 2 CUCM's connected by E1 via MGCP gateways, this is to simulate the PSTN network. I can see that on CUCM 7 this is not the case and media is sent directly to the MGCP gateway, on CUCM 8 media is sent via the CUCM to the MGCP gateway. I have since then added in a software MTP on the MGCP gateway for CUCM 8 and now everything hits the gateway as I have specified MTP is required on the phones profile. This was good but even when I make an internal call, everything hits the MTP instead of using IP-IP direct medial.

Please can someone advise what I need to do or if this type of behaviour is expected.

Many thanks,

Joe

[Chris Deren]

You need to review logs to see why MTP is being engaged, there are many reasons it can, most likely there is a DTMF mismatch.

[Joe Carey]

Hi Chris,

We've actually set everything now to out of band.

Can you tell me what logs and where to find them?

Many thanks and thanks for responding :)

[Chris Deren]

Is RFC2833 not available on your devices as that is typically what you want?

You need to pull the SDI/SDL (depending on your CUCM version) logs from RTMT under the CallManager service and look for the name of your MTP to see when and why it's being invoked.

[Joe Carey]

I've got RTMT 8.5 and I can see SDL Queue.

I am unsure where I need to go to check these messages. Can you help?

Cheers

[Ayodeji Okanlawon]

Hi,

You can use this link to learn how to collect cum traces..

https://supportforums.cisco.com/document/126666/collecting-cucm-traces-cucm-862-tac-sr

We can help you look at the logs and explain whats going on..

Please include the calling and called number and time of call..Check the traces to ensure that the call is there first before sending it over here.

What type of phones are you using? What dtmf method have you specified in your mgcp configuration

[Joe Carey]

We've found out that something has changed in CUCM 8 and onwards which is preventing this from working.

Does anyone know if it is possible to disable telephone-events in CUCM 8?

We're using our own endpoints which have been developed to work with and be supported by cisco. They are IP treading turrets.

[Ayodeji Okanlawon]

telephone-events are used to transport DTMF. You cant disable it. What you need to do is to configure your mgcp gateway to use the same dtmf method as your phones. What dtmf method does your phones support?

[Joe Carey]

We support RFC2388.

I've got the gateway configured as current gw config.

On one call manager I've not got that option as I'm using a 2621XM but on CUCM 7 I have a 2811 and I have the option to specify which one.

For the 2600 series I've configured the mgcp command to set the DTMF relay type

[Ayodeji Okanlawon]

You can configure dtmf relay to use nte on your  mgcp gateway with the ff:

mgcp dtmf-relay voip codec all mode nte-gw