Mobile phones can't make calls at first abroad, but later they can't answer the phone or receive text messages. What happened?

Because foreign SIM cards may be compatible with mobile phones, in order to ensure that your machine can use SIM cards normally, it is recommended to insert them as much as possible.

Whether the mobile phone can be used in non-Chinese mainland areas depends on:

1. Network mode supported by mobile phone;

2. Whether the network frequency band matches the network mode of the country and region you are going to, and whether it matches the network frequency band. If it matches, you can use the.

If you use a domestic mobile phone card, you need to contact the domestic operator to open an international roaming service and verify whether it supports the use;

If you use a non-Chinese mainland mobile phone card, you need to contact the operator to verify the network frequency band.