I has a voicemail from someone claiming to be my company's energy supplier and requesting an urgent call back. They left their name and it was a local UK dialling code. I returned the call and it was answered by a woman who didnt answer as a company would. It was just a 'hello'. I asked for the person who left the voicemail and the woman was very rude and said she needed to know where I was calling from before she could put me through. I ended the call there and then and didn't give any details but I'm concerned that maybe the number I dialled may rack up a huge bill or something.