A method for adjusting a transmission rate cap imposed by a service platform on one or more access links in a communications network comprising a plurality of access links (20a, 20b,20c), the method comprising: receiving service requests for delivery of data from requesting devices, wherein subsequent delivery of said requested data to each requesting device generates prioritised traffic over a selected one of the access links to the requesting device using a capped transmission rate; determining whether an adjusted transmission rate cap is to be imposed on one or more of the access links during delivery of said prioritised traffic to the respective requesting devices, and if so, generating source addresses (64a, 64b) for said data, comprising meta-data indicating said adjusted transmission rate cap to be imposed during delivery of said prioritised traffic, wherein the source addresses (64a, 64b) each comprise a URL from which requested data can be retrieved by the respective requesting device, and wherein said meta-data comprises a prefix to the URL for the requested data which indicates a maximum transmission rate to be used when streaming the requested data over each said access link (20a, 20b, 20c) to said respective requesting devices, reporting the source addresses to the respective requesting devices, processing each service request to determine one or more performance characteristics of the respective access link; the adjusted transmission rate cap imposed on each access link in said communications network serving a requesting device being determined in accordance with the said performance characteristics of said access link to enable a measurable quality-of-experience parameter for delivery of said requested data to be of equivalent transmission quality on each said access link. receiving service requests for delivery of data from requesting devices, wherein subsequent delivery of said requested data to each requesting device generates prioritised traffic over a selected one of the access links to the requesting device using a capped transmission rate; determining whether an adjusted transmission rate cap is to be imposed on one or more of the access links during delivery of said prioritised traffic to the respective requesting devices, and if so, generating source addresses (64a, 64b) for said data, comprising meta-data indicating said adjusted transmission rate cap to be imposed during delivery of said prioritised traffic, wherein the source addresses (64a, 64b) each comprise a URL from which requested data can be retrieved by the respective requesting device, and wherein said meta-data comprises a prefix to the URL for the requested data which indicates a maximum transmission rate to be used when streaming the requested data over each said access link (20a, 20b, 20c) to said respective requesting devices, reporting the source addresses to the respective requesting devices, processing each service request to determine one or more performance characteristics of the respective access link; the adjusted transmission rate cap imposed on each access link in said communications network serving a requesting device being determined in accordance with the said performance characteristics of said access link to enable a measurable quality-of-experience parameter for delivery of said requested data to be of equivalent transmission quality on each said access link.