CME transfer to another CME and back to original CME

Unanswered Question
Mar 5th, 2007

Here's the scenario.

A call comes in from the PSTN (site 1). The Call is set to forward to a user across the WAN to another CME System (using PLAR for example, to site 2).

The Person picks up the phone (site 2) and transfers the call to another IP phone in the original CME (site 1).

Assuming H.450 is setup, does the end state have the media stream within site 1 only? (from the router/pstn to the IP Phone the call was transfered to in Site 1).

The call is NOT hair-pinned right? It does NOT traverse the WAN right?

I'm fairly certain H.450 or even Cisco proprietary transfer doesn't hair-pin the call, but I need to make 100% certain it doesn't!

I believe hair-pin only occurs in devices that don't support either H.450 or Cisco proprietary transering methods.

The reason I'm asking is because I have a customer that is looking at centralizing their reception and doesn't want calls traversing the WAN when they are transfered back to the original site the call came in on.



I have this problem too.
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Paolo Bevilacqua Tue, 03/06/2007 - 07:30

Hi Paul,

I still have to test this personally, but I believe that either with SIP or H.323, the call would not be hairpinned.

palves Thu, 03/08/2007 - 16:25

No takers?

No one ever try this before?

Any help would be appreciated!

fred.s.mollenkopf Fri, 03/09/2007 - 10:42


This depends on a couple different factors, IOS version, CME version, command set applied. Can you post the two routers configurations so we can give our input?

High level, H.450.2 and SIP REFER, provide a direct post-transfer call between the Transferee and the Transfer-to. So in your example (Site 1 Phone 1 Transferee <-> Site 1 Phone 2 Transfer-to) and wouldn't take up WAN bandwidth like a Hairpin call would.

Please rate any helpful posts



palves Sun, 03/18/2007 - 19:44

Hi Fred,

It was more of a capabilities question. There is no actual configuration or IOS rev. (since it's a capabilities question).

A customer of mine is asking about this before comitting to the purchase.

I just wanted a second opinion. I know if it was within the same CME it wouldn't be hairpinned. However, since it's between 2 CME's, I'm not 100% sure it would work.




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