It has to do with a few issues, one of which is the SNR and signal clarity that can be acheived by sending tones down a plain old telephone line. There is just not enough bandwidth in a POTS connection to support higher rates of data flow as well.
56Kbps
A 56k modem may not connect at 56kbps due to line noise and interference, which can degrade the quality of the signal and reduce the effective speed. Additionally, the quality of the telephone line itself, including distance from the service provider and the condition of the wiring, can impact connection speeds. Lastly, the modem's own hardware limitations or the capabilities of the connected device can also prevent achieving the maximum speed.
The GPRS modem has a much greater bandwidth. It would be better suited to most tasks. However it would depend on what the connection was intended for. The wired modem may provide better reliability and lower ping in some situations.
Port speed is how fast the computer talks to the modem. Modem speed is how fast the modem talks across the phone line to the other modem.
The speed of a router is higher than that of a modem. However, the specifications of the modem do determine its speed.
The port speed setting for a modem, controls the speed that the computer communicates with its modem.
The modem will define the speed at which your will be able to access the internet connection. For example, if you have an ADSL modem, you will only be able to access speed at the modem max of 512k even though your telephone line has speeds up to 24,000k. Conversely, if your telephone line is only able to handle speeds upto 512k, having an ADSL2+ modem will not increase your speed. The technology for data transfer speed is in the cable sending and receiving data thus copper cables will be slower then fiber optics. A dial-up modem using the telephone line on analogue (instead of digital) will only transfer at a speed of 64k even though it is using the same copper cable capable of 512k.
Some of the steps for doing a cable modem speed test, include properly configuring the cable modem so that its running optimally, and using a speed test website to test the speed of the modem.
If we are talking dial up modems that is 56K in today's world. My first system had a 300/ 1200 baud modem that you stuck the telephone receiver into and closed the cover over it. Talking in the room would sometime make the system hang up. Times have changed
In the US modem speed is limited to 56K.
High Speed intelligent modem is 100bits of information per second.
speed of cellonics modem is 1000 times faster than normal modems