Why doesn't Unicom Mobile use traffic to save money and send text messages?

Unicom Mobile's SMS does not need traffic to save money, because the information channel they use is SMS center, not data network. Short message center is a short message transmission center provided by operators for users, which realizes the transmission of text messages between users through communication with mobile terminal equipment. When a user sends a short message, the short message is first sent to the short message center, and then the short message center sends the short message to the target user. In this process, only a little data traffic is generated, so there is no extra cost.