Therefore, the longer the wire between DSLAM and subscriber, the slower the maximum possible data rate due to the lower frequencies being used to limit the total attenuation (or due to the higher number of errors at higher frequencies, effectively lowering the overall frequency/data rate). The following is a rough guide to the relation between wire distance (based on 0.40 mm copper and ADSL2+ technology) and maximum data rate. Local conditions may vary, especially beyond 2 km, often necessitating a closer DSLAM to bring acceptable bandwidths: