3 Maximum transmission rate

The maximum transmission rate [1] refers to the maximum transmission rate that a MODEM can theoretically achieve, that is, the amount of data transmitted per second, in bps (bit per second). Here, it mainly refers to the dial-up connection speed, i.e. the data transmission rate from the server to the Modem, which only indicates the speed at which the Modem can connect to the ISP at the instant of connection. The standard 56K Modem refers to the rate at which a network connection is established. It is only a theoretical value that can be achieved in the most ideal situation. Due to the unavoidable noise of the telephone line, it is impossible to achieve a connection speed of 56K in practical use, as long as it is between 42K and 52K, it can be considered as a 56K Modem.
The dial-up connection speed will have different performance results depending on the external situation:
1) Related to server execution protocol
Modem may have a higher connection speed only when the server executes the corresponding protocol.
2) Related to the quality of the line
When a modem works, it first connects at the highest speed, and then quickly adjusts the connection speed based on the connection quality. Therefore, the quality of the line is a key factor that affects the modem connection speed. Regarding servers and their access terminals, as the network technology and hardware devices of large ISPs are constantly updated, if you connect to a server with better performance, you will obtain the smoothest data flow. Otherwise, on the contrary, this is also the reason why the rate of each access will change. MODEM with different performance will have different connection speeds under the same line and ISP conditions, so the quality of MODEM is also a relatively important condition.
The maximum transmission rate of MODEM can be divided into 9.6Kbps, 14.4Kbps, 28.8Kbps, 33.6Kbps, and 56Kbps. The common ones are 56Kbps, and the other low-speed MODEMs have been eliminated.