Which landline transmission medium is primarily used for voice communications?

Twisted pair cable is the primary landline transmission medium used for voice communications due to its design and properties. It consists of pairs of insulated copper wires twisted together, which helps to reduce electromagnetic interference and crosstalk between the pairs. This configuration is well-suited for the transmission of voice signals, making it the standard choice in traditional telephone networks.

One of the key benefits of twisted pair cables is their ability to support longer distances for transmitting voice signals without significant loss in quality. While fiber optic cables provide higher bandwidth and faster data transmission, they are primarily used for data communications rather than voice. Coaxial cables, although used in some telephone services and broadband connections, are more associated with television and internet services. Twinax cables are typically used for short-distance, high-speed communications within data centers rather than general voice applications. Therefore, twisted pair cable remains the most effective and widely utilized medium for voice communications in landline systems.