Telephone cables are generally multi-core copper twisted pairs stranded as star quad. They are single twisted pair cables, referred to as Voice Grade( VG) in English literature. According to the classification, they are category 1 copper cables for the transmission of voice signals.
Such a telephone cable can consist of two or four copper twisted pairs. The analog voice channels of the conventional telephone network are transmitted via the trunk lines, or the digitalISDN signals. The bandwidth requirement for conventional POTS is 3.1 kHz and is between 300 Hz and 3.4 kHz. For ISDN, the requirements are much higher and are at transmission rates of 64 kbit/s. In certain versions, the telephone cables can also support primary multiplex connections with up to 2 Mbit/s.
Both layer stranding and bundle stranding are used for stranding. The cable sheath of telephone cables is made of polyvinyl chloride( PVC) or polyethylene( PE) and is therefore correspondingly resistant.