How does SMS work?

the implementation principle of SMS-Short Message Service is simple, but the process of inputting characters on the mobile phone is rather troublesome. SMS has two outstanding advantages: the first is the store-and-forward mechanism. The work of transmitting data packets by SMS is completed by the short message center in the mobile network instead of the end user. If the user is not in the service area, the short message is stored in the short message center and forwarded to him after the user appears, which is not available in GPRS and other services. The second is the delivery confirmation mechanism. In the circuit-switched data environment, the connection is end-to-end, so the user can know whether the connection is completed and the data transfer situation. However, in the GPRS environment, the terminal attached to the GPRS bearer is always on, and it is ready to transmit or receive data transparently (relative to the user) at any time. In this way, the task of checking whether the data packet is sent successfully falls on the user, and the corresponding cost will be higher for each packet data service.