Phone Cloning

Hello,

A friend of mine suspects that her X has cloned her phone. She doesn't have proof, but odd things have happened to make her believe that.

My question is, what would he have to do to clone her phone. Can he just call the phone company (Fido) get the details by 'fooling' them, or would he need to get hold of her actual phone to read the SIM or something?

Also, what would she need to do to if her phone has been cloned. Would changing the SIM card be enough? Can the same phone be kept if the SIM card is changed?

She has an iPhone from Fido.

Regardless if the phone has been cloned, she wants to take the necessary steps to have her phone 'uncloned', without changing her phone number (if possible).

Only way for this to happen would be to clone the SIM card but the person would have to have access to the SIM for at least 5 hours or so. Painful process.

What are some of the issues going on?