How to understand Unicom's point-to-point SMS?

Peer-to-peer SMS is a user-to-user SMS, which does not distinguish between mobile, China Unicom and telecommunications. For example, I give you 50 point-to-point short messages a month, and you can send short messages to users of mobile, China Unicom and telecom, all of which are included in these 50 short messages! If you connect Unicom's SMS to Unicom separately, you will say that it is a peer-to-peer SMS!