A Digital Subscriber Line (xDSL) is used to connect Customer Premises Equipment (CPE) to a telecommunications network. The Customer Premises Equipment generates both Constant Bit-Rate (CBR) and Variable Bit-Rate (VBR) Packets. Each Frame of Packets from the Customer Premises Equipment is used to transmit up to a limited amount of CBR data, and VBR data is used, if available, to fill up the Frame. The limit on the amount of CBR data can be dynamically adjusted according to the need of the CPE. Similarly, and importantly, a limit on CBR data to the CPE can be adjusted dynamicaly according to the need for transmission of CBR data to the CPE. Advantageously, a guaranteed rate of transmission of CBR data can be maintained, even in the face of a flood of VBR traffic. Advantageously, this arrangement improves the quality of service on CBR traffic, such as Voice, and subject to the limit imposed by CBR traffic, allows a maximum amount of VBR traffic to be transmitted.