I want to ask what "peer-to-peer" SMS means.

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There is a detailed explanation

Peer-to-peer SMS refers to the business form of sending and receiving SMS between mobile phones. The forms of peer-to-peer short messages include intra-network short messages, inter-network short messages and international short messages. Point-to-point SMS is an independent user communication tool in theory. The communication tool can be a mobile phone, client software, PDA, etc. But no matter what point it is, the most basic purpose of point-to-point SMS is to realize two or more points of mutual communication, which is what people usually call chatting.

The basic function of point-to-point SMS service is chat, which can be divided into point-to-point chat, industry/enterprise application (in essence, one-to-many points), self-writing SMS, inter-network interoperability, international interoperability and so on.

As a brand-new and relatively independent way of interaction, SMS has become another way for people to obtain information. With the deepening of short message culture, point-to-point short message has become one of the main ways for people to chat remotely. Peer-to-peer SMS combines the characteristics of convenient use, wide range, storability and forwarding of mobile phones, and has the advantages of low price and no loss of information when turned off. It is short and pithy, convenient and quick, and can be said to be an "electronic note". At present, SMS is the only service in GSM network and CDMA network that does not need to establish an end-to-end service path, and it can be transmitted even if the mobile station is in a complete circuit communication state. Short message communication is limited to one message, in other words, the transmission of one message constitutes a communication. Therefore, the service is asymmetric, and it is generally believed that the initial mobile SMS sending and the mobile terminal SMS sending are two different things. This does not hinder real-time communication, but the system thinks that different messages are independent of each other, and the transmission of messages is always relayed by the Short Message Service Center (SMSC) outside GSM. Messages have destinations or origins, but they are only related to users and SMSC, and have nothing to do with other GSM infrastructures.

The convenience and quickness of point-to-point short messages are mainly manifested in the following aspects: from the perspective of communication, the means of communication are more convenient and the speed of communication is accelerated, which actually brings about the increase of communication frequency and the expansion of communication content. The effect of communication can get immediate feedback. No matter big or small, people can communicate at any time, from talking about something in the past in a few words to exchanging jokes and opinions. From the perspective of interpersonal communication, most famous enterprises are using SMS to communicate with their members and customers in time, which helps to form a stronger communication relationship. Compared with the traditional way of communication, the advantage of SMS is that it can communicate at any time, any place and any topic. More casual than talking on the phone, more mobile than chatting online. As a way of communication based on wireless network, SMS has the advantage of unknown Internet communication: you can make new friends through wireless QQ or SMS chat service opened by major websites under the premise of privacy.

Early peer-to-peer SMS was limited to the network of the same operator. However, with the rapid development of point-to-point short message service, the increasing number of users and the dispersion of user groups among different operators, this puts forward practical requirements for short messages between different operators, so operators gradually reach an agreement to allow their systems to communicate with each other. This is what people often say. In 2002, China Mobile and China Unicom reached an agreement, and the two companies realized the interconnection of national wireless short message service. The two competitors finally crossed a hurdle in the history of China Telecom, which made the turnover of its short message service soar rapidly. From the point of view of user experience, there is no difference between point-to-point SMS service and point-to-point SMS service in the network, except that a module called interworking gateway is added between systems of different operators, which is responsible for protocol conversion. With the diversified development of value-added services, SMS interworking has gradually developed into mobile-Unicom interworking, mobile-fixed network interworking, mobile -PHS interworking, domestic-international SMS interworking and so on.

Peer-to-peer SMS is a transaction, and it is a complete transaction from the initiation of one user to the successful reception of another user. Simply put, any link in this process fails, and the whole link fails. Figure 1. 1 illustrates the sending of short messages. Father sends a short message, and the information to be input includes the content of the short message and the number of the receiver (in early mobile phones, users also need to set the number of the operator's short message center), and the short message is transmitted to Xiao Qiang's mobile phone through the communication network. In the transmission process, the forwarding message can be stored, and when it is not received by Xiao Qiang mobile phone, the message can be temporarily stored; If the sending fails, the father will get a receipt of the sending failure; If Xiao Qiang receives the message, he can get the number of the receiver and the content of the message, so that a peer-to-peer transaction is over. When Xiao Qiang replied to this message, it was actually the beginning of another peer-to-peer transaction. Technically speaking, in the transaction of point-to-point short messages, message sending can be divided into two categories: MO/MT, where MO means message uplink, that is, people often say sending messages, and MT means downlink, that is, people often say receiving messages.

Figure 1. 1 Point-to-Point SMS Example

Point-to-point business processing flow is shown in figure 1.2. When a user sends a short message to a short message platform, the platform first authenticates the numbers of the sender and the receiver, including the sender's expense status and the receiver's status. If the sender owes money, it is forbidden to issue it; If the receiver cannot receive it temporarily, store and forward it; If all authentication conditions are met, a short message is sent. After the message is sent successfully, it sends a billing bill to the sender number and transmits the billing information to the billing system, which charges the user. In addition, the SMS system should provide users with perfect customer service, including the SMS value-added service to be mentioned later.