We have several systems in the field and we have just recently installed 2 new 12.5 systems (The rest are 12.0 and work just fine). The problem we are having is when we do blind transfer the call never goes to voicemail (Well, it does sometimes after 3 minutes... Yes I timed it... but not everytime). When the calling phone attempts the blind transfer it says Transferring and the called phone is ringing, after 2 minutes or so the calling phone stops ringing and it appears the call has been transferred. The called phone continues to ring for another minute and either goes to voicemail (I hear the voicemail prompt) or it just stops ringing and I (The caller) stays listening to hold music forever. It doesn't seem to be handset dependent as I first thought (We first discovered the issue on a system with many Cisco 7941's) but we then discovered it happening on a system with only Yealink T26P or T28P. We have a almost identical system to the T26P/T28P system running 12.0 and it has no blind transfer problem. I have NOT enabled the new Blind Transfer Call Back feature of 12.5. Transfers work if we direct to voicemail transfer OR it's transferred from the Digital Receptionist. I've been looking for solutions to the problem, so yes I have tried changing Codecs, Turning on and off "Supports Re-Invite" and "Support "Replaces" header" options, and the "I want to be able to accept more than 1 call at the same time". Help!