What is peer-to-peer SMS and how to use it?

In layman's terms: peer-to-peer short messages are short messages in the network of their own operators;

China Mobile Point-to-Point refers to mobile-to-mobile SMS, Unicom Point-to-Point refers to Unicom, and telecom Point-to-Point refers to telecom-to-telecom.

If the mobile phone is sent to Unicom, it is not a "point-to-point SMS", but an off-network SMS.