VCS SIP to H.323

[lowfell]

I've tried to make this easier to understand. basically this H.323 to SIP via VCS. i want to understand the call flow & the transforms that take place

So is this the call flow ?

H.323 endpoint to Sip example
ABCD123>>>>>>>>>>>SIP doesn't understand ABCD123 i better append domain>>>>>>ABCD123@SIPDOMAIN>>>>>>SIP Endpoint

Then is the return like this?

SIP return back to H.323 example

ABCD123@SIPDOMAIN>>>>>>>>>>>>H.323 doesn't understand ABCD123@SIPDOMAIN H.323 doesn't understand
ABCD123@SIPDOMAIN i better strip the domain ABCD123>>>>>>>>>>H.323

1.Can someone please tell me if this is correct

2. is i the same process for voice calls from CUCM to SIP through VCS ?

[lowfell]

Anybody help here please?

Thanks in advance.

[Ammar Saood]

why don't you register H323 devices using URI Format? e.g.

H323 ID= register.h323@example.com

SIP URI= register.sip@example.com

then add a transform to append "@" so it will standardize the dialing.

and if need be, to call H323 devices without @ domain, you can achieve this by stripping @ domain using search rules.

HTH,

Please rate and mark the answer if helpful.

[lowfell]

Hello Ammar. Thank you for trying to make sense of this.

I understand about the process to create the transforms etc. What I'm trying to understand is the Call Flow involved?

The first transform appends the @domain      to the H.323 endpoint

the second transform STRIPS the @domain  FROM the H.323 endpoint

What I don't understand is at what point the Strip transform kicks in, is it on the return path from the call or am I misunderstanding this?

[Ammar Saood · Accepted solution]

anytime, any request reaches Expressway, rules are applied in this Order. it doesn't matter if its an inbound or an outbound call.

1. CPL Policies/Rules

2. Transforms

3. Search Rules

So Transform will be applied first and then Search rule's (strip, append, prefix) will be applied.

suppose you have a transform that appends "@example.com" to dialed Aliases.

you have 2 search rules in place

a. Search alias@example.com for SIP URI devices

b. Strip domain and Search alias only

H323 ID device calling SIP URI devices

lets say you dialed "lowfel.sip.ex90@example.com"

1. your dialed alias already contains SIP domain. Domain will not be appended at the transform stage. 

2. sip registered device will be searched as per search rules(a).

SIP URI device calling H323 ID devices

lets say you dialed "lowfel.h323.ex90"

1. Domain will be appended (because of transform). so it will become lowfel.h323.ex90@example.com

2. H323 registered device will be searched as per Search rules (b). it will strip the domain before calling H323 ID of the device.

HTH

AMMAR

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[lowfell]

That's great. thanks Ammar. I thought it worked that way, but wanted clarification. thanks for your patience & time,

[Ammar Saood]

Best practice is to append the @domain at transform level to standardize your dialing scheme for SIP and H323 devices.
We usually don't add the transform to strip domain. Stripping is more practical to be done at Search rules level.