Not sure if this is a normal or expected behavior.
Setting up BLF on a Yealink T29G. The lights respond correctly. The odd part is when transferring a call using the BLF. After answering the call, I press the BLF, the call is moved to the correct extension. However, if the person calling hangs up before the VM or expected person answers, there is a ghost call returned to the extension from whence the BLF originated.
In other words, the call is ringing and the party disconnects before the call can be completed. If this happens, then it appears that the system is trying to re-route the call back to the last known good location.
Using FreePBX 13.0.163, on CentOS from Sangoma installation download.