If your device isn't working properly, you can try several solutions to solve the problem.
In most cases you can solve the problem by following these guidelines:

If your mobile phone is locked to another service provider and you're trying to use a Swisscom SIM card, the display will tell you that your SIM card is invalid.

Solution: Before you can use a Swisscom SIM card, you need to unlock your mobile phone using an unlock code. To get the unlock code, contact the service provider that locked your mobile phone.