CUCM 8.x is on HQ. There is brnch VG at branch. There is 7911 phone conneted in branch which is registered to cucm in HQ. There are separate pots line available if this phone calls to PSTN or I can reach to this phone calling from PSTN.
If I call this phone either internally or from PSTN and try to xfer the call from that phone to another internal extension it works. But when this phone calls to PSTN and then try to xfer the call to internal extension call can not xferred as the xfer button is grayed out. What could be the issue.
