An process for working a material in which a reverse thermal fluid is used as a cutting fluid and, as a result of heat generated during the working process, the fluid increases in temperature above its transition temperature and viscosifies and thickens. Such applications include, but are not limited to, frequency down-conversion, frequency up-conversion, enhanced signal reception, unified down-conversion and filtering, and combinations and applications of same. Where possible, a call processor adapted according to embodiments may implement some of the same call mastering functions with respect to calls using VoIP infrastructure links as for more traditional call using PSTN links. According to embodiments of the present invention, the quantization of an input vector is done by introducing the modification vectors for the base codebook vectors, therefore the memory amount of the base codebook vectors is reduced effectively, and the calculation amount is merely the calculation amount required for going through N codebooks.