How do I choose a default phone number?

You have to choose a number to use when you’re making a call or sending a message to someone who is not saved in your contact list.

With iOS 13, you need to choose which mobile plan you wish to use for iMessage and FaceTime. Bear in mind that in iOS 13, you can choose one of the numbers or both.

On this screen, please select the default number for your line. If you prefer, you can choose the number that will only be used for mobile data. Your other number will then be the default one for your line. If you want your iPhone to use mobile data from both your plans, depending on coverage and availability, activate the “Allow cellular data switching” option.