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Back to Back PRI with MGCP Gateways

I?ve got a 3825 with T1 voice modules (RJ45)..

They are configured as MGCP managed by a set of call managers.

On Friday, I have to integrate this gateway with an old Mitel switch, which will be used during a 2 year phased migration to get calls between old and new systems? To prepare for that, I have setup the T1s back to back for testing/validation that my MGCP config is working.

I can configure those T1s as ?T1 CAS? trunks, and put a crossover cable between them, make a route pattern 3.xxxx and have the call go out one T1, and back in the other, and it works great? The problem is that there?s no caller ID information set. In the trunk configuration screens, there are fields to specify that callerID should, or should not be sent, etc, but it just doesn?t go.. I?m not terribly surprised by this, because I don?t think there?s any protocol defined for the ?plain? T1 to transfer callerID.. I guess I was just hoping that somehow, it would work! :-)

What I would REALLY like to do, is to put these two T1s in PRI mode, since I *KNOW* a PRI can send callerID, but to do that, I have to have one of the ports emulate the CO-side switch.

When configured as PRI signalled T1s, I saw a pull-down that said something like ?Protocol Side? or ?Protocol Mode? (Sorry, it?s not configured as PRI right now, so I can?t look at the verbiage), and the selections were ?Network? and ?User?, which sound to me as if it?s EXACTLY what I need, but I couldn?t get it to come up to even test? It acted as if I had a timing issue, even though I hadn?t changed any timing parameters from the T1 CAS settings that worked (One internal, one external).. I was getting intermittent amber alarms, and the trunk never came up.

Unfortunately, I can only change the configs on this thing early in the morning, because yesterday, some of the MGCP control I was doing through the CM gui actually bounced their WAN T1s that are in the same router, so now I have to be careful!!

What I would like, is to get a definitive answer to whether two MGCP controlled T1s can be back to back in a PRI signaling mode, and/or if there?s another way to get callerID across a T1 link without one end of it being the CO itself. Ultimately, it won't be a cisco-cisco crossover, but rather a cisco-mitel solution, so whatever I come up with MUST be standards based, so at least I can have something to expect the Mitel engineer to be able to do..

Any help would be GREATLY appreciated!!!

-Steve

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Back to Back PRI with MGCP Gateways

Steve,

Never tried a back-to-back PRI with both routers being MGCP. I have in my lab two routers back to back with one router being edge voice gateway controlled by mgcp and the other being a pstn simulator. On the edge voice gateway the following configs exist.

controller t1 1/0

pri-group timeslots 1-24 service mgcp

ccm-manager mgcp

mgcp

mgcp call-agent

int s1/0:23

isdn switch-type

isdn incoming-voice voice

On the PSTN router (which emulates a PSTN switch)

controller t1 1/0

pri-group timeslots 1-24

int s1/0:23

isdn protocol-emulate network

isdn switch-type

isdn incoming-voice voice

This should work for back-to-back PRI pretty well.

3 REPLIES
Blue

Re: Back to Back PRI with MGCP Gateways

a rather cheap isdn simulator may do the trick for plugging your PRIs into.

you need an isdn switch (or simulated) to get the layer2 up for the device.

Re: Back to Back PRI with MGCP Gateways

You should be able to do with the Mitel off their T1 card.. if it's an SX200. I think you need to change the configuration of the T1 so that the D channel on the CAS T1 is set for data. Basically, think about from the angle of how Mitel connects two T1 switches together... what is the protocal they use. Then you use the same config on the MGCP gateway.... Or of course, check with the Mitel engineer that it can do QSIQ. QSIQ will send the data of the call over to the MGCP gateway also. This a CAS T1 feature or possible option

But may have to go to with the AdTrans external device to do your PRI to PRI simulation....

Re: Back to Back PRI with MGCP Gateways

Steve,

Never tried a back-to-back PRI with both routers being MGCP. I have in my lab two routers back to back with one router being edge voice gateway controlled by mgcp and the other being a pstn simulator. On the edge voice gateway the following configs exist.

controller t1 1/0

pri-group timeslots 1-24 service mgcp

ccm-manager mgcp

mgcp

mgcp call-agent

int s1/0:23

isdn switch-type

isdn incoming-voice voice

On the PSTN router (which emulates a PSTN switch)

controller t1 1/0

pri-group timeslots 1-24

int s1/0:23

isdn protocol-emulate network

isdn switch-type

isdn incoming-voice voice

This should work for back-to-back PRI pretty well.

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