This will read like victim blaming, but the OP must have realised at some point being with BT Mobile well before the power cut, that the phone signal might be iffy or inadequate and problems both receiving and making calls were perhaps inevitable. Unless of course they've purchased a basic mobile phone that just gets switched on/used every now and again.
The OP clearly has little understanding of how mobile phones and signals operate, as evidenced by their belief that they thought keeping their mobile phone charged, it would somehow just work irrespective. As they are now aware, if there's none to little phone signal, it isn't going to work no matter how charged up your phone is.
To anyone else reading this, use the coverage checker in the earlier link and decide if coverage is adequate before commiting to a particular provider. Remember too, that there are a lot of MVNO's out there who piggyback off one of the big four networks. Choose wisely.
