When you call someone, the system says, "The call reminder is for you. We will notify you by SMS as soon as possible. This call is free." Why?

It may be because there is no signal, or the phone is turned off. This didn't receive your call, and then you turn on the opposite phone and there will be a text message.

Incoming call reminder means that when the mobile phone is turned off or out of service area, the incoming call information is saved for you within 24 hours through the incoming call reminder platform. When the phone is back to normal, all incoming messages will be sent to your phone in the form of short messages, so that you will no longer worry about losing important calls. Incoming call reminder means that when the mobile phone is turned off or out of service area, the incoming call information is saved for you within 24 hours through the incoming call reminder platform. After the mobile phone returns to normal, all incoming messages will be sent to your mobile phone in the form of short messages.