Hi,
I have problem with AT530P after updating to Asterisk 1.6.0.22. UNHOLD stops working. (UNHOLD worked with Asterisk 1.6.0.9)
A - AT530P
B - PSTN/SIP Provider/Phone from other vendor (f.ex. X-Lite, Grandstream)
B call A.
A pick up the phone.
A press Hold and hear tone, B hear music.
A press Hold again and can talk, B hear music.
Please help me 
Michal Januszewski