asterisk users - Feb 2011 - Aastra phones cannot transfer calls?

I have two Aastra phones, a 6730 and a 6757, both connected to Asterisk
v1.6.2.1. They can call each other's extensions (and make and receive
calls otherwise), but they cannot transfer calls, not even to outside
extensions on the PSTN. The procedure I use is to accept a call on one
phone, press the transfer button, dial the other extension, and then press
"transfer" again after the second extension answers. The transfer
appears
to work until I press "transfer" the second time, at which time the
Aastra
phone gives the error message "Transfer Failed".

These same phones have no trouble performing this operation on Asterisk
v1.4.23.1.

Is this an issue with Aastra phones, or is it a problem with Asterisk 1.6?

At 12:12 PM 2/15/2011, you wrote:
>I have two Aastra phones, a 6730 and a 6757, both connected to Asterisk
>v1.6.2.1. They can call each other's extensions (and make and receive
>calls otherwise), but they cannot transfer calls, not even to outside
I'm running 1.6.2.16.1 and have three Aastra 480i phones and have had 
no problem at all with transfers. Have you considered trying a newer version?

Ira