I'm not familiar with this phone but I am with Nokias. Make sure numbers aren't shown under two different names. This can happen if you're using both phone and sim memories together. Make sure "Mum" for example is always "Mum" on both memories and not "Mum" on one and "Mum mobile" on the other. this will prevent the name from displaying when they call. If you select memory options you can choose sim or phone or both. This though isn't likely to be the problem if it's a new phone unless you've manually stored numbers since you got it, and that person was already on your sim. Does any of this make sense? Hope so!