Dial Up Modems can achieve higher transfer rates.

Once upon a time, dial-up modems had the slowest transmission speeds but with data compression they are making a come back. With a wireless modem, external modem, or internal modem that has the ability to compress data higher data transfer rates are possible. This is how many internet providers are now able to offer high speed internet because they are compressing the information before it is transferred through the phone line. As long as the modem on the receiving end is able to decompress the data in the same manner it is receiving it then the transmission rate can be increased up to five times faster than typical data transmission rates as many ISPs advertise.