I also have experienced a similar problem from UK to South Africa. Partner wrang me numerous times whilst away with no problems however, on one particular afternoon (there were bad storms)he rang me 10 times and on 2 occassions he spoke to a man! However for the particular times he rang i had no missed calls or received calls on my mobile, hardly if any signal and i was on my own with my phone. I’ve checked his call logs and they do say he rang my number and was connected- however this was not the case with my call logs and certainly no man had access to my phone. I rang orange they said it was practically impossible for this to happen- but it did!!!!!!!!!
I am no longer in South Africa to contact the network provider. Please help solve this mystery?