Why is calling a short message service? What does this mean?

Short message service is a kind of call forwarding.

SMS calling service means that all incoming information will be automatically recorded when the customer is turned off or out of service area. When the customer turns on the phone, the incoming call information will be sent to the customer's mobile phone in the form of SMS.

The appearance of short message service is generally the reason why the other party's mobile phone is turned off or there is no signal. Another reason is that if the other party is a dual-card mobile phone, this will happen when you dial another number of the other party while the other party is on the phone.

SMS call forwarding service is a short message forwarding function, which provides customers with voice-like call forwarding. Customers can use this service as long as they apply for SMS call forwarding function and set the forwarding number as required. After SMS call forwarding, the mobile phone will no longer receive peer-to-peer messages from other mobile phone numbers, but directly forward them to the mobile phone with the call forwarding target number.

Someone calls you when your phone is turned off or there is no network signal, and you will receive the message when you turn it on or there is a network signal.