Bit-stream Access

Bit-stream access refers to the situation where a wireline incumbent installs a high-speed access link to the customer's premises (e.g., by installing ADSL equipment in the local access network) and then makes this access link available to third parties, to enable them to provide high speed services to customers. This type of access does not entail any third-party access to the copper pair in the local loop.

The incumbent may also provide transmission services to its competitors, using its Asynchronous Transfer Mode (ATM) or IP network, to carry competitors' traffic from the digital subscriber line access multiplexer (DSLAM) to a higher level in the network hierarchy where new entrants may already have a point of presence (e.g. a transit switch location). Bit-stream handover points thus can be at various levels:

• Handover at DSLAM
• Handover at ATM-PoP
• Handover at IP level

Bit-stream access is nowadays considered a key tool for opening competition in the broadband market. It enables competitors to offer their own products to consumers even if they do not operate the local loop (the last mile). Bit-stream access allows the new entrant to use the high-speed modems and other equipment provided by the incumbent and thus avoid maintenance and investments into the local loop. This affects the economics of the service and places restrictions on the type of modems that the customer of the new entrant can buy or rent.

The main elements defining bit-stream access are the following:

• High-speed access link to the customer premises (end user part) provided by the incumbent and transmission capacity for broadband data in both direction, enabling new entrants to offer their own, value-added services to end users;
• New entrants have the possibility to differentiate their services by altering technical characteristics and/or the use of their own network.

Thus, bit-stream access is a wholesale product consisting of the access (typically ADSL) and “backhaul” services of the (data) backbone network (ATM, IP backbone).