Use other numbers to send and receive text messages.

Here's the thing: you send someone a short message, which is not sent directly to the other party's mobile phone by electric signal, but passes through the short message center, where the other party's location is confirmed and then sent to the other party's mobile phone.

If the number format of the SMS center is wrong or not set, there will generally be cases where you can only receive but not send. It is best to set the number of local SMS center, which can reduce the occurrence of problems such as loss and delay of SMS.

The landlord's situation should be that the setting of the SMS center in the machine was not affected when the machine was swiped. There is no SIM card in the SMS center number. Some computers will use the SMS center number of the network by default when receiving network signals, but others will not and need to be set manually.