Integrating Aastra 44xx (4422) sets with Asterisk over SIP

Hi,

Any one to succesfully integrate Aastra 44xx (4422) sets with Asterisk over SIP ? My sets can receive calls but when dialing other parties, even when the call is answered and the remote observes a connection, Aastra sets start showing BUSY and no voice transmission is available.

Thanks in advanced.

Did you have any success with using these phones?
I can’t even log in from my Aastra Dialog 4425 using SIP… Not sure what’s going on.