I have asked this question on here before. Signal is available on the diggle side, almost up to the marsden portal but is lost until the other side of the station. I considered that mobiles were piggy backing off the network rail GSM-R but apparently this is not the case. There hasnt been a definitive answer from anyone yet as to why it works. Nearby morley tunnel unfortunately doesnt have any reception.
Wi-fi hasnt been inplemented yet, its a franchise commitment for the next holder, hence why stagecoach, not First were carrying out the survey although authorisation also came from first. The guy still had to have a train ticket oddly enoigh......