I'm having trouble with Yealink T28P handsets not passing the inbound caller ID when calls are transferred. e.g. call comes in with caller id 035551234, receptionist on ext 800 answers and blind transfers to ext 801, 801 rings and shows incoming call from ext 800 instead of 035551234.
This only happens when pressing transfer and then a BLF extension, if transferred by dialling the extension number the original caller ID passes fine.
Also works fine when answered and transferred from a non Yealink handset.