How to set callerid for attended transfer?

Asterisk Asterisk Support
1

I have asterisk 13.13cert2, pjsip, a simple dialplan:

extensions = {
    ["from-local"] = {
        ["_."] = from_local
    },
    ["from-transfer"] = {
        ["_.*"] = transfer
    }
}

function from_local(context,extension)
    app.Set("TRANSFER_CONTEXT=from-transfer")
    app.Dial("PJSIP/" .. extension .. ",,tT")
end

function transfer(context, extension)
    app.Set('CALLERID(name)=Transfer')
    app.Set('CALLERID(num)=1111')
    app.Dial("PJSIP/" .. extension .. ",,tT")
end

And several endpoints:

[9716]
   type=endpoint
   transport=udp-transport
   aors=9716
   auth=9716
   context=from-local
   disallow=all
   allow=alaw
   direct_media=yes
   dtmf_mode=auto
   rewrite_contact=yes
   callerid=9716 <9716>

[9717]
   type=endpoint
   transport=udp-transport
   aors=9717
   auth=9717
   context=from-local
   disallow=all
   allow=alaw,g729,ulaw
   direct_media=yes
   dtmf_mode=auto
   rewrite_contact=yes
   callerid=9717 <9717>

[9718]
   type=endpoint
   transport=udp-transport
   aors=9718
   auth=9718
   context=from-local
   disallow=all
   allow=alaw
   direct_media=yes
   dtmf_mode=auto
   rewrite_contact=yes
   callerid=9718 <9718>

I’m calling from 9716 to 9717 and transferring to 9718. In the case of blind transfer, invite (header From:) contains the information that i set using the CALLERID function. But in the case of attended transfer, invite (header From:) contains the information of the person who made the transfer, and not what i set using the CALLERID function.
How to change callerid when use attended transfer?

2

I’m assuming that these are SIP transfers, not features transfers.

Asterisk cannot tell the difference between an independent call on the phone’s second line and a transfer,so there is no way for it to to associate the caller ID of the original caller, or even know that the call is being made as a transfer.

If you never make second line calls other than as part of a transfer, you might be able to use group counts to detect a second line outgoing call.

Also _. is bad practice (also matches h, e, i, t, s, etc.) and will produce a warning, and _.* is not valid dialplan pattern syntax.

3

This transfer by codes from features.conf:

[featuremap]
blindxfer => *2
atxfer => #

Dialplan is given only to illustrate my problem.