What does it mean to tell the mobile phone user in the form of peer-to-peer SMS when calling the mobile phone?

Conclusion: He will say the same thing without calling others.

Note: This is only a mobile value-added service. Specifically, when the user's mobile phone cannot be connected, the short message center (MSC) will send a P2P message to his mobile phone to remind him of XX:XX:XX. Call from (your) mobile phone 13XXXXXXX, please ask him to call back. This service is similar to SMS calling service.