Abstract: A method is disclosed for establishing and adapting communication link parameters in xDSL transmission systems. The method determines a frequency allocation scheme that makes the delivery of both xDSL services and traditional telecommunications services possible, and uses information about service bit-rate requirements and the deployment characteristics of a given local loop to select an optimal combination of symbol rate and transmission modulation density that is capable of delivering desired xDSL services. The method includes the steps of establishing communication between xDSL termination units, and determining a maximum transmission modulation density that can be used for a plurality of predetermined symbol rates. One method of performing these steps is a symbol rate stepping method in which communication is initiated at a fraction of the final symbol rate, and the symbol rate is iteratively stepped up until the final symbol rate is reached.