Abstract: A characteristic of a local loop is used to estimate the loop's data carrying capacity. The characteristic is measured and applied to a table previously stored in memory which contains values relating the characteristic to downstream data rates. Using interpolation when required, an estimate of the data carrying capacity of the local loop is estimated based on the measured characteristic. The measured characteristic may be, for example, the input impedance or the DC resistance of the local loop.

Abstract: An apparatus for isolating ADSL signals from POTS signals includes a single low pass filter for filtering the POTS signals for all POTS terminal devices within a customer's premises. The low pass filter is mounted within a line isolation device (LID) connected between a telephone jack and an ADSL transceiver. The customer's wiring is altered so that the ADSL and POTS signals are supplied to blue (B) and yellow (Y) lines, rather than the typical connection to the red (R) and green (G) lines, and the LID returns filtered POTS signals on the R and G lines. The telephone jacks within the premises remain connected to the R and G lines and receive the filtered POTS signals from the LID. Instead of reconnecting incoming signals to the R and G lines upon removal of the ADSL transceiver, a jack is preferably used which automatically shorts the B and Y lines to the R and G lines, respectively, upon removal of the LID from one of the telephone jacks.