My home phone with TPG(NBN) cannot call a particular family member's mobile number- I keep getting a recorded message saying that number is not available. Strange this is, I can call that mobile number using my own mobile phone. Even stranger, when I use my home TPG/NBN phone, I can call other mobiles e.g. my own or my wife's, just not this particular family member's mobile number. Yet I can call that elusive mobile number if I use my mobile (just not the home TPG/NBN phone). Anyone got any ideas why ?