[Asterisk-Users] How to xfer calls or is my setup wrong?

[Mark Benson]

I am having problems transferring calls from one sip extension to 
another - the extensions use various phones hardware/software.

 From what I can tell I should just be able to press # and then dial an 
extension to blind xfer a call right? How do I do attended xfer?
Either the phones (for this test I have tried xlite and budgetone102) 
are not sending DTMF correctly or something else is amiss...

The call comes in from an external number via IAX2 (0870xxxxxxx) which I 
can answer on any of the ringing extensions no problem. But when I need 
to xfer that call I am more or less stuck. I have read various posts and 
something about *8# ? seemed to partially work one on the grandstream 
but I haven't been able to reproduce that...

The CLI doesn't show anything odd...

Any ideas?