[asterisk-users] PRI Callerid Passthrough

dk at donkelly.biz dk at donkelly.biz
Wed Mar 18 09:19:30 CDT 2015

This depends on what you mean by “not involving the service provider.”


If you are literally forwarding calls that come in on the PRI back out on the PRI, the most efficient way is with Two B-Channel Transfer (TBCT). Check it out in the wiki.


You need to make sure your carrier supports the feature.


When you want to do a “transfer,” you have an incoming call alerting or answered, you initiate an outgoing call (using the originating ANI). You initiate the TBCT and the CARRIER completes the transfer, disconnecting both of your B channels. The carrier will later notify you when the transferred call is done, but I don’t think Asterisk handles this directly. 


Note that at least one of the calls must be answered when you initiate the transfer. If you are doing “unattended” transfer, you will, typically, leave the incoming call alerting until the outbound call answers, then complete the transfer. An “attended” transfer would generally answer the incoming call, play a message, do some IVR doodling, or chat with an agent then initiate the transfer.


Have fun





From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Rizwan H Qureshi
Sent: Wednesday, March 18, 2015 7:16 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] PRI Callerid Passthrough


Thanks AJ and David,

We were actually using GSM gateways by setting busy forward number on the SIMs and just giving busy signal on every incoming call, telco took care of the forwarding and the line was free within seconds. Now we need to scale up the setup but GSM gateways a very very expensive if we want to scale upto a 1000 DIDs, which means thousand SIMs and a gateway/gateways big enough.




On Wed, Mar 18, 2015 at 3:43 PM, A J Stiles <asterisk_list at earthshod.co.uk> wrote:

On Wednesday 18 Mar 2015, Rizwan H Qureshi wrote:
> Hi All,
> I have to forward incoming call on PRI back out to PRI but I need the
> original Callerid to passthrough. Is it possible with DAHDI PRI cards
> without involving the service provider?
> Thanks

It depends who your service provider is!

Any PRI card can send the commands down the D-channel to set any caller ID you
like, but it's still up to the telco whether or not they will honour your
request.  I know the hard way that BT will only let you identify with a number
you're entitled to use.

Also, remember if you have a call coming in on a PRI line and going out on
another PRI line, that's eating two of your thirty lines .....


Note:  Originating address only accepts e-mail from list!  If replying off-
list, change address to asterisk1list at earthshod dot co dot uk .

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Best Ragards

Rizwan H Qureshi


V: +971 (0) 528272154




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