H323 and IP Based Dialing - CMS

[madhav.kumar.bhardwaj12]

We are using SIP endpoints, CUCM 11.5, CMS 2.1, Expressway C and Expressway E B2B and MRA clusters. SIP based calling works fine with SRV records etc but we are not able to understand the call flow for H323 and IP based dialing for B2B calls. 

I assume outside video endpoints which does not support SIP then they will use H323 and they will be dialing at number@IP address format like 1234@cisco.com ? Is that correct ? If yes then i assume i just need to match search rule with H323 protocol ?

How only IP based dialing works ? Client is looking for public based IP with default IVR system where they can enter space/meeting number.

[Nick Halbert-Lillyman · Accepted solution]

You can configure a "fallback alias" on Expressway-E, or a transform or search rule to change an IP address into a valid SIP URI, e.g. 123@yourdomain.com.

You would then configure a route pattern to send "123" to CMS, and configure "123" as your IVR number on CMS under "General Settings".

The call flow is:

1. H323 user dials Exp-E IP address, sends Exp-E the call

2. Exp-E converts the IPO to 123@yourdomain.com, sends to Exp-C

3. Exp-C already has a search rule to send @yourdomain.com to CUCM (or you could send to CMS directly to skip step 4)

4. Route Pattern sends "123" to CMS

5. CMS has "123" as its IVR number, so directs the call to its IVR.

[madhav.kumar.bhardwaj12]

Thanks Nick for solution. Appreciate it. It worked for me. I just wanna inputs from your side about IP based dialing from inside to outside.

So my company users want to dial external IP address from inside and that worked with temp domain like 10.10.1.1@doamin.com ------> CUCM-----SIP domain routing----Domain.com-------Expressway C---remote domain.com and change to only IP address--------Expressway E------Route only IP address 

but now my company want to call string@IP address like ---2322322@10.10.1.1 so i am not sure how to route the same from CUCM to Expressway E--

[Nick Halbert-Lillyman]

The best thing to do would be to encourage the far end to move to a current, standard system with DNS :)

Failing that, you'd have to do it on a per-IP basis using transforms or search rules on one of the Expressways.

E.g.

1. Dial 2322322@external-company.com from CUCM endpoint

2. On Expressway, transform a suffix of @external-company.com to @1.2.3.4

If you're dialling the same organisation frequently, this could work OK but is obviously a bit of a pain if you need to do it all the time to different companies.

Cisco, rightly or wrongly, has taken the stance that there's no reason to support native IP dialling from CUCM, given that DNS based dialling has been the standard for many years.

[madhav.kumar.bhardwaj12]

Thanks Nick again for information. It seems that URI@IPaddress solution is not possible or it is manual process as you described for every new call.

[Patrick Sparkman]

To allow CUCM registered endpoints to dial via IP, take a look at Dial IP Addresses from Endpoints Registered to CUCM with VCS / Expressway Configuration Example.