CUCM 10.5 integration with AVAYA CM6 via H323 intermittent call issue.

[nagerona1]

We are experiencing intermittent issue on calls between Avaya and Cisco, On failed calls, call will connect with no audio on both sides then after a few seconds it will automatically dropped. We configured the Avaya CM6 as an H323 gateway on the CUCM. Trusted relay point is enabled on H323 gateway using a registered MTP resource from the voice gateway. On successful calls, I am seeing a remote port and remote ip(the IP address of AVAYA resource) upon issuing show sccp connections and show voip rtp connections on VG. but on failing calls, remote port and remote ip is 0 and 0.0.0.0. Anyone familiar with this issue? Thank you

[Suresh Hudda]

Why didn't you use sip for integration, is there any specific reason ? I think sip is ideal here and sip trunk directly can be configured between avaya cm and cucm without using voice gateway in between.

Suresh

[nagerona1]

Hi Suresh,

Thanks for your reply, the problem is their current Avaya system is not capable of using SIP trunk. that's why we opted to use H323. This is a direct integration without Voice Gateway in between, Our CUCM only use the Voice gateway as a MTP resource.

Niel

[Mohammed al Baqari]

I believe you are right. Avaya need additional hardware for SIP integration.

Now, I know avaya support slow start only (fast start not supported). So this means that h245 negotiation is failing but h225 is successful because the call was completed.

Check the following:

1. Codec used? Integrating with Avaya using G729 is a nightmare.

2. Make sure that Avaya is acting as MTP (inserted in the media path). Don't let avaya phones connect directly to Cisco phones. This procedures behavior similar to your description. There an option in avaya to achieve this.

3. Check who many MTP sessions have you configured and the MTP codec is matching the one configured for failed calls. Make sure that you have enough MTP sessions and the call isn't failing because of out of resource error.

4. In case of any security device between Avaya and Cisco, make sure that all ports are allowed between Avaya subnet and Cisco Subnet. H323 slow start uses random ports for h245 phase, hence you need all ports to be allowed.

Note: Without MTP supplementary services will fail between Avaya and Cisco.

Try the above steps and see how it goes.

[nagerona1]

Hi Mohammed,

Thanks for your suggestions. 1. Actually we are using g729 on the integration since this is already the setup they are using and this is going thru MPLS. 2. We already checked the required MTP on the H323 configuration. 3. I checked on the CDR and I see cause value of 47 which indicate ,Resource unavailable. this is my config on the router:

dspfarm profile 2 mtp
codec pass-through
maximum sessions hardware 10
maximum sessions software 10
associate application SCCP

dspfarm profile 1 transcode
codec g711alaw
codec g711ulaw
codec g729br8
codec g729r8
codec ilbc
codec g729abr8
codec g729ar8
maximum sessions 10
associate application SCCP

4. We'll check the firewall on Cisco and Avaya side. are these ports the same for CUCM version 10.5? 

https://supportforums.cisco.com/discussion/10010436/callmanager-h323-tcpudp-ports 

http://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-communications-manager-callmanager/43881-ccm-tcp-udp-ports.html

Thanks,

Niel

[Mohammed al Baqari]

Niel,

My advice is to allow all ports between Cisco Subnet and Avaya Subnet. Don't limit ports as per the sheet. Start with this and confirm that firewall isn't problem.

Also, when the call drops check the command 'sh sccp conn' and check whether you have 10 active mtp sessions or not.

[nagerona1]

Noted Mohammed,

as of now, I am the only one using the connection to Avaya. I have attached the sample output of the sh sccp conn

Thanks,

Niel

[Mohammed al Baqari]

Thx. Also make sure that the connection is bypassed from any inspection device and disable any h323 inspection on the firewallls