UL20251 is a type of multi-conductor telephone cable that is commonly used in telecommunications applications. It is a type of cable that contains multiple insulated conductors that are twisted together in pairs or groups of pairs, with an overall shield or jacket for protection. The cable is often used to connect telephone systems, modems, and other communication devices in both residential and commercial settings.

UL20251 cables are designed to meet certain safety and performance standards set by Underwriters Laboratories (UL), a third-party testing and certification organization. These standards ensure that the cable is safe to use and will perform reliably in its intended application. In particular, UL20251 cables are rated for low voltage applications and are designed to provide good noise rejection and signal integrity, which are important factors in maintaining clear and reliable telecommunications connections.

UL20251 is a specification for multi-conductor telephone cable. The cable is designed to be used in low-voltage applications, such as telephone and intercom systems.

The UL20251 specification sets the standards for the mechanical and electrical properties of the cable, including its temperature rating, voltage rating, and flame resistance. It also specifies the maximum capacitance and resistance per unit length of the cable.