Category 1 cable (Cat 1) a.k.a. voice-grade copper is a misnomer, probably adopted by those who assumed that TIA set up "Categories" for all types of cables originally defined by Anixter, the distributor, under the grades called "Levels." TIA-568 only recognized cables of Category 3 ratings or above. Anixter "Level 1" was a grade of unshielded twisted pair cabling designed for telephone communications, and was the most common on-premises wiring.
Cat 1: Previously used for POTS telephone communications, ISDN and doorbell wiring.
Cat 2: Previously was frequently used on 4 Mbit/s token ring networks.
Cat 3: used for data networks using frequencies up to 16 MHz. Historically popular for 10 Mbit/s Ethernet networks.
Cat 4: Provided performance of up to 20 MHz, and was frequently used on 16 Mbit/s token ring networks.
Cat 5: Provided performance of up to 100 MHz, and was frequently used on 100 Mbit/s Ethernet networks. May be unsuitable for 1000BASE-T gigabit ethernet.
Cat 5e: Provides performance of up to 100 MHz, and is frequently used for both 100 Mbit/s and Gigabit Ethernet networks.
Cat 6: Provides performance of up to 250 MHz, more than double category 5 and 5e.
Cat 6a: Provides performance of up to 500 MHz, double that of category 6. Suitable for 10GBase-T.
Cat 7: This standard specifies four individually-shielded pairs (STP) inside an overall shield. Designed for transmission at frequencies up to 600 MHz.
