Which type of device provides an Internet connection through the use of a phone jack?

The type of device that provides an Internet connection through the use of a phone jack is a Dial-up Modem. Here are the steps:

1. The Dial-up Modem is connected to the computer and the phone line.
2. When you want to connect to the Internet, the computer instructs the modem to dial a specific number provided by your Internet Service Provider (ISP).
3. The ISP's modem answers the call, and the two modems communicate and establish a secure connection.
4. The computer can then send and receive data over the Internet. The data is transmitted over the phone line by the modem at each end.
5. When the connection is no longer needed, the call can be ended to free up the phone line.