Please set my mobile dada

See thes three support articles:--> If you see Invalid SIM or No SIM on your iPhone or iPad

and/or:--> How to unlock your iPhone for use with a different carrier

and/or:--> If you see No Service, Searching, or SOS on your iPhone or iPad

If you already tried (to no avail) all the steps provided in above articles, I suggest that you make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> https://locate.apple.com/choose-country-region . After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

You will need to contact your carrier for help with their service, Apple can't help you.