How can I check the number if my mobile phone has no phone bill?

You can try self-service inquiry in the following ways:

One way is to insert the mobile phone card into the mobile phone and use the mobile phone system to automatically identify the local phone number (which needs the support of the mobile phone).

For example, if you insert the card into the iPhone, you can go to Settings-Cellular Mobile Network to check.

The second method is to ask relatives, friends and colleagues around you to see if you can save a number.

The third method is to check Cato. Cato usually writes down his mobile phone number.