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Re-direction - sip-codes


Mads Mortensen
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Hi,

 

 

we have been testing around with redirection, and we have a problem.

It do not seem the PBXSIP in any way indicate (when a call is re-directed) that it is a rediretion coming through.

 

So plese, can any one tell me if PBXnSIP do (or do not) supports these codes: http://www.voip-info.org/wiki/view/SIP+Response+class3

 

 

please advise

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are you able to terminate calls at all ? try to do an outbound call useing the same trunk,

i had it that my dial plan wsnt good and the pbx have send an invite and got a 480 so it didn't redirect the call.

 

 

That is no problem at all :-)

 

My problem is just that (from what we can see) there is no indication that the call has bee re-directed.

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I remember we used to put a "R:" in front of the display name. Not sure what happened to this one.

 

 

Somehow we need and indication, that the call that is showing up on (e.g.) the mobile phone, is redirected from the PBX.

Normally when you redirect one of these codes: http://www.voip-info.org/wiki/view/SIP+Response+class3

are included in the direction info.

 

This means, if I call the cell directly on its own number A-numbers will be displayed "XXXXXXXX" BUT if the call i redirected to the cell phone, the A-number will (do to the codes mentioned above) be displayed "-->XXXXXXXX"

 

Then you are aware that you (with the cell phone) is paying for the redirection.

 

So far we have been tracing in the files, but can not see any indication in the files, when a call is redirected.

 

 

I hope the above made it more clear, so any ideas??

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Somehow we need and indication, that the call that is showing up on (e.g.) the mobile phone, is redirected from the PBX.

Normally when you redirect one of these codes: http://www.voip-info.org/wiki/view/SIP+Response+class3

are included in the direction info.

 

This means, if I call the cell directly on its own number A-numbers will be displayed "XXXXXXXX" BUT if the call i redirected to the cell phone, the A-number will (do to the codes mentioned above) be displayed "-->XXXXXXXX"

 

Then you are aware that you (with the cell phone) is paying for the redirection.

 

So far we have been tracing in the files, but can not see any indication in the files, when a call is redirected.

 

3xx codes usually treated as pure error respones from carriers, which makes a lot of sense. There are huge billing problems with 3xx-codes, imagine redirection to cuba. There is no authentication of 3xx responses, for starters. The other problem is that 3xx responses can have more than one contact, meaning that the carrier would have to support forking.

 

The other technical problem is that the call is often already connected (the initial INVITE has been answered with a 2xx class response already). Then most carriers will ignore 3xx-responses. In this case the PBX would have to send REFER, which has the similar problems as 3xx, and which also most carriers don't accept.

 

The way to indicate redirection is today probably History-Info (RFC4244). Even if the PBX would use this header, I doubt that the cell phone provider would do anything useful with this.

 

Last not least, both with 3xx and REFER you cannot fork the call to the desktop phone and the cell phone. If you use this method, we are always talknig about a simple and dumb redirection to the cell phone. For example, you will definitely loose the "1" feature for connecting the call.

 

That is why we simply play back the caller-ID when the user picks up the call on the cell phone and decided to use the "1" feature to connect the call.

 

I know from a user perspective, these answers are not very satisfying. In the end, only the cell phone provider can change the picture.

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3xx codes usually treated as pure error respones from carriers, which makes a lot of sense. There are huge billing problems with 3xx-codes, imagine redirection to cuba. There is no authentication of 3xx responses, for starters. The other problem is that 3xx responses can have more than one contact, meaning that the carrier would have to support forking.

 

The other technical problem is that the call is often already connected (the initial INVITE has been answered with a 2xx class response already). Then most carriers will ignore 3xx-responses. In this case the PBX would have to send REFER, which has the similar problems as 3xx, and which also most carriers don't accept.

 

The way to indicate redirection is today probably History-Info (RFC4244). Even if the PBX would use this header, I doubt that the cell phone provider would do anything useful with this.

 

Last not least, both with 3xx and REFER you cannot fork the call to the desktop phone and the cell phone. If you use this method, we are always talknig about a simple and dumb redirection to the cell phone. For example, you will definitely loose the "1" feature for connecting the call.

 

That is why we simply play back the caller-ID when the user picks up the call on the cell phone and decided to use the "1" feature to connect the call.

 

I know from a user perspective, these answers are not very satisfying. In the end, only the cell phone provider can change the picture.

 

 

So basically it is not possible for us to see if a call is redirected or not.

I do not see the problem you are ref. to billing wise.

Basically we just need a indication that the calls has been redirected!

 

But anyhow, it is s*** - as we are suppose (law) to offer this.

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So basically it is not possible for us to see if a call is redirected or not.

I do not see the problem you are ref. to billing wise.

Basically we just need a indication that the calls has been redirected!

 

Well, if you are using RFC3325, then the PBX will keep the original caller-ID in the From header. No problem if your carrier can present this as the caller-ID. I think in the SS#7 world there are two caller-ID anyway, the one to display to the user and the one that should be used for billing. But AFAIK practically all cell phones only display the first one.

 

If you are the carrier, you can do this relatively easy. The PBX even sends a (proprietary) header with a "Related-Call-ID" which indicates the original call leg for reference. But I guess that does not help you...

 

The billing problem is probably that carriers generally love to bill twice for redirected calls. Double the revenue!

 

From a legal point of view, an audible indication that the call eas redirected is already there. I am not a lawyer, but it might be enough to make the legal department happy.

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