This site contains information about BT's networks and services. The site is primarily aimed at providing technical information to equipment manufacturers in order to allow them to design equipment that is compatible with BT's networks and services. The site also provides notification to Service Providers about some BT services which may be of particular interest to them.
The BT publications on SINet are specific to BT's networks and services. When other operators provide services that seem comparable, the characteristics of their customer interfaces may well be different. Ofcom requires all operators to notify and publish the technical specifications of their customer interfaces. If you have any queries regarding the contents of other operator's specification(s), these should be raised with the operator in question.