Call transfer from SIPX not working

A call comes into my Asterisk box and I dial a customer’s SIPX machine. Afterwards, the SIPX box sends a SIP REFER message to my Asterisk to transfer the call. This doesn’t work.

Here is the trace:

ast  ------ INVITE --------->  sipx
ast  <----- 100/180/200 -----  sipx
ast  ------ ACK ------------>  sipx
ast  <----- REFER -----------  sipx
ast  ------ 202 Accepted --->  sipx
ast  ------ NOTIFY --------->  sipx
ast  ------ BYE ------------>  sipx

As you can tell from the call flow, the Asterisk doesn’t try to transfer the call at all.

Can anyone tell me if Asterisk properly handles REFERs? I’ve seen some SIPX docs that say it can’t, however I can’t really find anything in the forums about it.