asterisk users - Jan 2017 - Attended Transfer using AMI on PJSIP

I need to make attended transfer work via an AMI request.

Based on data from a Cisco trace from another system which successfully does an
attended transfer, the Refer-To header requires the following format
<sip:destination;Replaces=destcallid%3Bto-tag%3D_____%3Bfrom-tag %3D____>

Using the PJSIP_HEADER support, I am abte to retrieve everything I need with the
exception of the to-tag.

1. I retrieve the Via address from the destination channel.
2. I retrieve the Call-ID for the destination call using the PJSIP_HEADER
support.
3. I retrieve the From header's tag field from the destination channel.

Is there a way to retrieve the tag from the To header?  When I use the
PJSIP_HEADER support to read the To header, it does not include the tag field.


Is there a better way to retrieve this information for the Refer-To Replaces
portion?

Have a great day!
Dan