I know im beating a dead horse, but, has anybody come accross an issue with 3rd party sip endpoints (Yealinks) not being able to do an attended transfer. External call (on SIP Trunk) is answered on a T46U and gets transferred to a T31G, using attended, the initial internal call is connected and voice is there, but as soon as the transfer is completed there is no voice. If I do I blind transfer, voice gets heard.