Got 1 phone which is faulty! no audio/sound!
we got 3 offices, lets say Site A where the CM is located), site B & site C.
this faulty phone is in Site A, when used within site A, it's working well.
However when calling Site B & C, there's no sound/audio. testing shows that its codec is also g.729 as a normal call between each site. also only this phone have this problem! so I would say it's not the firmware (correct me if i'm wrong). also done a factory reset, but still the same.
Any more troubleshooting ideas?