Speed versus distance
Balanced pair cable has higher attenuation at higher frequencies, hence the longer the wire between DSLAM and subscriber, the slower the maximum possible data rate. The following is a rough guide to the relation between wire distance and maximum data rate. Local conditions may vary, especially beyond 2 km, often necessitating a closer DSLAM to bring acceptable speeds:
* 25 Mbit/s at 1,000 feet (~300 m)
* 24 Mbit/s at 2,000 feet (~600 m)
* 23 Mbit/s at 3,000 feet (~900 m)
* 22 Mbit/s at 4,000 feet (~1.2 km)
* 21 Mbit/s at 5,000 feet (~1.5 km)
* 19 Mbit/s at 6,000 feet (~1.8 km)
* 16 Mbit/s at 7,000 feet (~2.1 km)
* 1.5 Mbit/s at 15,000 feet (4.5 km)
* 800 kbit/s at 17,000 feet (~5.2 km)