Category 2 (CAT-2) is a UL designation for inside telephone cable used primarily for voice and low-speed data transmission. It is also referred to as Level 2 cabling.
Category 2 cabling represented an incremental improvement over Category 1, offering limited data capabilities while still supporting analog voice communication. Constructed from unshielded twisted pairs (UTP) of copper conductors, CAT-2 cables were rated for frequencies up to 4 MHz, suitable for low-speed data systems such as early token ring networks and computer-to-computer connections. Despite this improvement, its performance was still inadequate for Ethernet or broadband applications.
As network technology advanced, CAT-2 quickly became outdated, giving way to Category 3 cabling, which could support 10BASE-T Ethernet and higher data rates. Though now obsolete, CAT-2 remains a reference point in the historical evolution of structured cabling systems, marking the transition from purely voice-based networks to integrated data communication infrastructure.
Category 2 cabling was originally classified by Underwriters Laboratories (UL) and referenced in early telecommunications standards before the formalization of TIA/EIA structured cabling categories. It has since been retired from active recognition in modern standards as performance requirements evolved.
Introduced in the 1980s, Category 2 emerged as businesses began combining voice and low-speed data systems. With its 4 MHz bandwidth, it supported early token ring networks and low-data-rate applications. However, as Ethernet technology gained popularity, CAT-2 could no longer meet the performance demands of new communication networks and was soon replaced by Category 3 cabling and higher-rated systems.