This is done inside the TelCom core - you have no control over that on the device. That's also why headers from normal (non-mobile) endpoints including WiFi ar

This is done inside the TelCom core - you have no control over that on the device. That's also why headers from normal (non-mobile) endpoints including WiFi are considered unreliable for such information. All that might soon change with the use of IP6 addresses.