We have come a long way from the early days of the computer since 1964. The mobile phone can be a mini computer in itself hence can be cloned / hacked.  

Phone cloning involves placing a computer chip into the target mobile telephone, allowing the electronic serial number (ESN) of the mobile phone to be modified. The ESN is normally transmitted to the cellular company in order to ascertain whether the mobile phone user is the legitimate owner of that phone. [1]

To days TOI carries a disturbing article

Next time if you get a missed call starting with +92; #90 or #09, don’t show the courtesy of calling back because chances are it would lead to your SIM card being cloned. The telecom service providers are now issuing alerts to subscribers -particularly about the series mentioned above as the moment one press the call button after dialing the above number, someone at the other end will get your phone and SIM card cloned. [2]

Sadly as expected the crooks are also active endangering the careless use of the mobile phone for storing any personal info.