How to send short messages with old mobile phone cards

As long as the mobile phone card is plugged into the new phone, the old phone will be turned off when not in use. Theoretically, it is impossible to read and connect with the operator without a SIM card, but the mobile phone may display an error. If these phones are Internet phones, you can still use the original number without going through the SIM card, but you need to connect to the network, that is, WIFI. See if this is the case with you.