Retain Origional Caller ID on blind transfer

When a client calls in, their caller ID displays on the reception phone LCD, the receptionist then answers the call… right pretty simple stuff.

Then she transfers the call to a staff member and the LCD displays the receptionist caller ID on the staff members phone LCD. This makes no sense!

The receptionist is not using “attended” transfer (i can understand that this would display the reception caller id… since she is actually calling the staff member). Its simple, the lady answers the call… presses the “Transfer” key on phone… she then presses the number of the staff members extension … then OK.
This has got to be about thee most basic, basic, basic feature of ANY PBX in the world… why can’t Asterisk keep the Caller ID of the original call that the receptionist answered. The CDR’s are even correct. Bother lines in the CDR show the original callers Caller ID.

I tried using “f” in the dial command… nope. I tried “o” in the Dial command… nope. I tried sendrpid=pai in the sip.conf… nope.

The closest I got was under some condition - cant remember now - i got an error saying something about extension XXX not supporting “UPDATE”. I take it Asterisk was sending an update for the caller ID… donno wasn’t tracing at the time.

Asterisk 1.8
Yealink and Gigaset Phones.

On the Dial() aplication use the option o
Uses the caller ID received on the incoming leg of a call as the caller ID for the outgoing leg. This is useful if a call is accepted and then transferred; in the normal case, the caller ID of the initial recipient is used for the outgoing leg, which can be confusing to the ultimate recipient. For example, say Joe calls Mary; Mary decides that Joe really needs to speak to Don and transfers the call. If option o is set, Don will see Joe’s number on his display when Mary transfers him, instead of Mary’s number.

I assume these are SIP phones. Is this a SIP transfer? If it is, you need to understand that some SIP phones implement all transfers as attended transfers. With a SIP attended transfer, there is no way to tell that this isn’t a simple second line call out until the transfer is completed.

Although you may think you are requesting a blind transfer, the phone may initiate an enquiry call, and complete it with REFER/Replaces, when it is answered.

Spot on there david55!! I am using Yealink (T20) to answer the call, and yes it seems to be attending the transfer.

So i did a little test - same thing, call comes in, pick up, but this time use ## to initiate a blind transfer (from features.conf), then the extension number… and perfect - caller ID shows.

I didn’t even have to use any “o” or “f” in the Dial command.

Any advise how to set the Yealink to do an actual blind transfer. (The Yealink documentation is really bad!)

Thanks for the assist.

This feature definitly depends heavily on the phone. I personally have experience with AAstra phones, which do this beautifully. Just like you described. You only need to set “sendrpid=pai” in Asterisk and the correct Caller ID is displayed on the Aastra phone schreen on transfers and call pickups that are initiated by the phone.

You shouldn’t need Remote-Party-ID or P-Asserted-Identity for true blind transfers.

I totally agree with you. But in practice when doing blind transfer from IP phone, you usually get behaviour that you already described :wink:

[quote=“david55”]I assume these are SIP phones. Is this a SIP transfer? If it is, you need to understand that some SIP phones implement all transfers as attended transfers.