UK ITSP "Gamma" - Header Requirements for Diverted Calls

[TONY SMITH]

Hi,

Does anyone on here use the UK provider "Gamma" for SIP trunking, and if so have they managed to get diverted calls from call forward or single number reach, to display the original calling party?   By which I mean if I call from my mobile to a DDI that has been call forwarded, I want the final called party to see my mobile as the calling number. 

If so, were there any special settings needed either at your end or requested from Gamma?

On a new install we are finding that diverted calls show the billing number on the diverted leg.  I've tried various combinations combinations, for example sending the diverting number in PAI so that Gamma one their valid numbers there.

And just to confuse things further I checked another pre-existing Gamma site and it works perfectly there with no tweaks at all, they just send the original calling number in the "From:", "Contact", and PAI headers, with no diversion header.

So it seems there may be a setting at Gamma's end as well.

Any insight appreciated,  Thanks.

[Mohammed al Baqari]

Hi,

You can confirm that by checking the invite message from your gateway to
the 2nd call leg. If that has Diversion-Header, Remote-Caller ID, PPI or
PAI as original caller then its gamma overriding it. Otherwise, you have
wrong setting which is making the caller id as diverting phone instead of
original caller.

I am assuming that you don't have STUN and calls are hairpinned on your
gateway.

Next, if gamma is overwriting it, check with them for their settings and
what header they expect to see to reflect the original caller.

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[TONY SMITH]

Thanks.

I agree, correct headers to match the ITSP requirements is going to be the key, but as usual with service providers it's proving difficult to get an answer.   So at the moment for a diverted call we show ..

Original calling number in the From and Contact headers

Diverted number in Diversion and PAI, which I would have thought should have satisfied Gamma requirement to see what they think of as a valid number in PAI.   

However - we have a work around.  In my notes from a Gamma install years ago, there was reference to an option they referred to as "CLI Flexibility".  Asking for this to be enabled has fixed the issue.  

[Mohammed al Baqari]

Gamma usually is very responsive in my experience. I used them and they
always assisted. In my deployments they usually request for PAI which they
mention in their document.

Give it a shot with them and see how it goes.

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[TONY SMITH]

Thanks.  As already mentioned we have had PAI set from the start.  As for responsive, I've had no answer at all from them.  Only from the reselling partner who was able to set "CLI Flexibility" but not answer my questions.