Is it possible to safely have incoming BT landline calls automatically transferred to a non BT mobile ?
Yes, you can pay for call diversion to any number including a mobile.
Bear in mind that you will be charged for the cost of the call as if it originated on your own landline.
Yes, you need the Call Diversion add on which is £5.57 a month, plus the cost of the calls. In effect you would be dialling your mobile from your land line and charged accordingly.