Access fee

A special fee that local phone companies are allowed to charge customers for the right to connect with the local phone network. (Cingular)

Adjacent channel interference

Adjacent channel interference

Signal impairment to one frequency due to presence of another signal on a nearby frequency. (Cingular)

Adjacent-channel interference or ACI is interference caused by extraneous power from a signal in an adjacent channel.

Note 1: Adjacent channel interference may be caused by inadequate filtering, such as incomplete filtering of unwanted modulation products in frequency modulation (FM) systems, improper tuning, or poor frequency control, in either the reference channel or the interfering channel, or both.

Note 2: Adjacent-channel interference is distinguished from crosstalk.

Source: from Federal Standard 1037C and from MIL-STD-188

(Wikipedia)