Excuse me, what is on-hook SMS?

Hang-up SMS is an active push service for enterprise SMS advertisements. After an enterprise's telecom fixed telephone (telecom mobile phone) applies for this service, it can easily publish short message advertisements according to this number. When the calling party dials the number and hangs up, according to the dialing situation, for example, connected, busy, no answer, etc. , the "on-hook SMS" service system will extract different SMS advertisements with number settings and send them to the caller in real time. The terminal receiving SMS advertisements can be a telecom mobile terminal, or a mobile terminal of operators such as China Mobile and China Unicom.