* If you're asking if a phone charger uses mains power, then the answer is yes**. Phone chargers plug into a wall outlet, which is part of the mains power system.

* If you're asking if a phone charger is mains power, then the answer is no**. The phone charger converts the mains power into a lower voltage and current that is safe for your phone.

So, while the phone charger uses mains power, it doesn't provide mains power itself. It acts as a transformer, converting the high-voltage electricity from the wall outlet into a lower-voltage electricity suitable for your phone.