No. There are other methods of connecting to the internet, such as cable internet and 3G.
You need at minimum, a telephone line.
Through the Telephone Line.
DATA Transmission is done through SLIP (Serial Line Internet Protocol) & PPP (Point to Point Protocol) Protocols to enable computers to interact with Internet over Telephone Line.
software
You don't. The laptop has to connect to the internet separately, either directly through a telephone line (for dial-up service) or a broadband DSL/satellite/cable modem. If you want to connect both machines at the same time, you need a router between the modem and the two machines. (NOTE: this cannot be done with a single telephone line, only with broadband)
The modem on your computer must connect to your Internet Service Provider's server over a land telephone line. You connect the computer's modem to a telephone jack as you would a telephone.
Its when you connect through the Internet just through your Telephone Line (No Router) Its very slow and costs a lot. If you want it instead of a Router, Go to your Nearest Computer Store and speak to them about the Price and the Cables Needed.
Dial up uses a telephone line to connect to the internet and is much slower than cable.
If you mean can you network computer to computer through a phone line, adhock, then if both computers have a dial up modem then yes. It's kind of a pain tho, and not every modem could do it. If you mean connect to another computer via internet over a phone line then yes if it has a dial up modem. DSL does use the phone line for access to the DSL modem.
A modulator demodulator (MODEM)
Telephone line. Either unplug telephone and connect lead to computer while online, or get double-socket ADSL connector so telephone is unaffected.