A message distribution center and Intelligent Delivery Agent are implemented in a wireless Internet gateway interposed between content providers and a wireless carrier to subjectively examine and direct messages via SMTP based on desired rules using standard SMTP Gateway and other well-known protocols. The input audio signal is inspected to check whether it is a foreground frame or a background frame; the detected background signal is further inspected according to the music eigenvalue and the decision rule. Some aspects relate to fitting a surface to the match scores wherein the surface represents illuminant parameter values other than the candidate illuminants, solving for an extremum of the surface and determining chromaticity coordinates of the extremum. A first determination of whether or not the predicted value has exceeded a first predetermined value is made. The released pressure results in closure of the valve when mechanical movement is produced by the pressure operable device in response to the release of pressure.