Probably one of my most commonly requested features is to be able to transfer directly to an individual's VM instead of transferring direct to the extension. Since the defaults in 3CX don't include the ext number on the BLF key, I can't simply tell them to dial *4 and then the extension without suggesting keeping a print out of all the extensions. Yealink has a "prefix" type for the BLF key that works perfectly for this. Assign the key, add the *4, and show them how to be agile enough to press that and the ext blf. However, I can't deploy it to the phones in a permanent fashion without hard coding this into a template. This then makes it a "custom" template and annoying for administration and support down the road for a feature that's actually supported by the phone.