Systems and techniques for communications wherein a data packet is transmitted over at least one time slot from a transmission site, a value is computed from an initial value and information, the initial value being a function of the number of time slots of the data packet transmission, the value and the information is transmitted from the transmission site, the transmitted value and the information is received at a receiving site, the value from the received information is recalculated, and the number of time slots of the data packet transmission is determined from the calculated and recalculated values. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.