Which technology is specifically associated with dial-up connections over telephone lines?

The technology that is specifically associated with dial-up connections over telephone lines is PPP, or Point-to-Point Protocol. PPP is a data link layer protocol that facilitates the encapsulation of network layer protocols over point-to-point links, typically used for dial-up internet connections. It establishes a direct connection between two networking nodes and can provide features such as authentication, encryption, and compression.

Dial-up connections operate over traditional telephone lines, and PPP is integral to this process, allowing the transmission of IP packets over these connections. This makes PPP highly relevant for the context of connecting to the internet via modems over phone lines, distinguishing it from other technologies listed.

In contrast, ISDN (Integrated Services Digital Network) and ADSL (Asymmetric Digital Subscriber Line) involve different methods and standards for digital transmission, while VDSL (Very-high-bit-rate Digital Subscriber Line) provides faster speeds over existing telephone lines but is not directly related to the dial-up method. Therefore, PPP is the protocol most directly tied to dial-up connectivity.