Mitel 3300 Cisco VCS

[medrt]

Creating a SIP trunk from a Cisco VCS to Mitel works, however calls from
VCS Side to Mitel allows only 1 call.  The next call the VCS gets back a response "503 service unavailable".
Mitel to VCS allows multiple calls.
 
I can create a 2nd trunk, and it allows a second call to the Mitel.  But obviously that is not a solution, just a test.
If seems that a trunk to Mitel behaves more like a channel than a trunk.
 
I have created numerous trunks to numerous platforms, but this is a first for Mitel.  I don't have any knowledge of the Mitel, but I am guessing something is not configured correctly on that side.

Thank you for any assistance you can provide.

[bluewhite4]

Creating a SIP trunk from a Cisco VCS to Mitel works, however calls from
VCS Side to Mitel allows only 1 call.  The next call the VCS gets back a response "503 service unavailable".

What do you have inbound calls to the Mitel pointed to?

I can create a 2nd trunk, and it allows a second call to the Mitel.  But obviously that is not a solution, just a test.

How did you create a second trunk? Do you mean you created a second SIP Peer Profile?

If seems that a trunk to Mitel behaves more like a channel than a trunk.

I guess I don't know what you mean by this.

[medrt]

Thank you for the response.
I am blind on the Mitel side.  I do not have access to it, although I can ask the Mitel tech to look at things, or modify things.

What do you have inbound calls to the Mitel pointed to?

I'm not sure exactly what you mean.  But this Mitel 3300 has been in place for a while servicing UA's and PSTN calls without a problem.  The new addition is adding the VCS and a SIP trunk between the two.

On the VCS side, I setup a SIP trunk the points to the IP address of the Mitel.  There is a rule that dictates that anything prefixed by 9 goes out that VCS SIP trunk to the Mitel.  I was testing to the PSTN. 

UA -- registered to --- VCS --- SIP Trunk---- Mitel ------ PSTN
This call works. Trying a second call from a second UA using the 9 prefix fails as I described.
I then added another SIP trunk to the Mitel and used 8 as a prefix.
If I use the two different prefixes (8 and 9) I can get 2 calls simultaneously.

Coming from the PSTN, I can make two or more simultaneous calls to UA's that are registered to the VCS.

I guess I don't know what you mean by this.

What I am used to is creating a trunk between 2 SIP registrars and then many calls going over the trunk.  (Which is what seems to happen from the Mitel, but not to the Mitel)
What is happening from the VCS to the Mitel, is only 1 call (I said channel in the original post), at a time is allowed.

Hopefully that clears things up a little.