Which technology enables digital transmission over standard copper phone wires?

Digital Subscriber Line (DSL) is the technology that enables digital transmission over standard copper phone wires. DSL works by using a higher frequency band for data transmission, which allows it to coexist with voice calls on the same line. This technology is widely used to provide high-speed internet access without interfering with traditional telephone services.

In contrast to DSL, Fiber To The Premises (FTTP) utilizes fiber-optic cables, not copper wires, so it does not fit the criteria of the question. Integrated Services Digital Network (ISDN) provides digital transmission over copper lines as well, but it is primarily designed for voice and data services rather than focusing on high-speed internet access like DSL does. Dial-up is a much older technology that connects to the internet over standard phone lines but operates at significantly lower speeds than DSL, thus not representing the modern digital transmission capabilities.