Phone calling by its own

Hi, Need desperatly your help.

Since tonight my Iphone 4s is calling different persons from my contacts and I haven't even touched my phone!

Sometimes I receive also fake calls from different numbers but when I answer there is nobody on the other line.

It is late in the night and I am afraid that I am calling and disturbing people even not knowing it.

I cleared everything on Iphone and restored it but it keeps doing the same thing.

Please help and tell me what can I do?

PS: My Iphone is factory unlocked, no jailbreak or any other things in it.