[IPOffice] Not hear ringback tone when call from outside to ipphone E129

[phuongdt]

I have a ip office system 9.0.3 with E129 and 1608, my system use 16 CO line.
when I call from outside to E129, caller not hear ringback tone but E129 ringing.
when I call from outside to 1608, i can hear ringback tone.
Inside, call to E129 can hear ringback tone

I use VMPro to create greeting. the call will transfer to user when caller press DTMF.
ex: press 0 transfer to Reception
press 151 transfer to E129 phone



Please help me