Number of concurrent calls SIP trunk

[j.huizinga]

Hi,

I have a SIP trunk configured on callmanager 4.1. This SIP trunk connects to an outbound dialer. This works fine, but is seems that I can have only 24 concurrent calls on the SIP trunk.

Is this correct, or is there a parameter to change this?

Thanks,

JH

[gogasca]

The limitation is not for the SIP Trunk we technically dont limit the number of calls in CUCM for a SIP Trunk, the limitation seems to be in the PSTN device (dialer) sounds like you have a T1 CAS or T1 PRI (T1-PRI -1) or....you are using MTP required and you no longer have MTP resources but sounds more like first problem...please clarify whats the exact call flow for those 24 calls.

Thanks

[j.huizinga]

Thanks for your quick response.

The configuration is that the dialer makes outbound calls over its own ISDN lines (E1 PRI),and uses the SIP trunk to connect to agents (IP communicator). The people that configure the dialer claim that the cannot open more than 24 channels because the callmanager denies this.

I am not using MTP required (unchecked).

What callmananger trace can tell me the possible error between dialer and Callmanager?

thanks,

Jan

[reidg · Accepted solution]

I've found that mtp can still be brought in, even when this is unticked. Use RTMT to confirm if mtp resources are being used. If they are, then if I remember right there are only 24 software mtp per server. In service parameters, under Clusterwide parameters - sip device: there is a field : 'fail call over sip if mtp allocation fails' if this is true, then this could be your problem.

[j.huizinga]

Grant, you are so right about this!

I checked with RTMT and saw that each call over the SIP trunk was consuming an MTP resource. And 24 is the maximum.

Do you know if this 24 is per callmanager server or per cluster?

Thanks for your answer!

Jan

[reidg]

its 24 per server, sorry for delay hadn't noticed the response.