Attended transfer feature codes


I am having difficulty with Feature Codes for Attended Transfer.

What works:

  1. Incoming call (A) is answered by B
  2. B presses *2 and calls C, C picks up. A is now on hold
  3. At this stage, B pressing *2 joins A & C. B pressing *3 makes a 3-way conference call between A, B &C.

What doesn’t work:
B cannot disconnect from C and get back to the call from A. If C hangs up on B, B gets back to A.
But I don’t know how B can get back to A without C’s involvement. ** does not work for me.

This Asterisk page ( suggests
atxferabort=*3 (or some other feature code…)
to abort an attended transfer.

However placing this line in
does not work. The *3 3-way code remains in effect.

Any ideas?
It would be great to know where the definition of *3 is coming from FreePBX. It does not appear in Feature Code Admin.
It would also be great to be able to define the atxferabort Feature code and use it.