UK Broadband Usergroup FAQs (frequently-asked questions)

IPStream is a service where the user traffic is routed longer inside BT's managed network therefor number of users connected to the exchange does not affect the connection speeds, as it is a completely balanced network

With DataStream, the ISP takes one or more 'virtual path' (VP) circuits to each local exchange so they can manage contention themselves.

Most ISPs use DataStream to deliver services with high contention ratios spread over very small numbers, so often DataStream will deliver worse performance, however technically it is capable of more customised services, including 1:1 contention.

A passive Microfilter does not actively filter and only does so when a signal is being sent down the line, active Microfilters have more circuitry and filter all the time. Active Microfilters tend to be more expensive and allow for more devices to be connected at any one time. The only BT approved Microfilters are active filters.

Strictly speaking no, although you will need to buy an RJ-11 to BT converter as all cables provided by Us are RJ-11 to RJ-11. Also if you wanted to use another device (phone, fax etc..) on the line in the future you would need a Micro filter.

Your ADSL modem/router reports 576Kbps as this is the speed it is connecting at, the 512Kbps is the real speed you are getting (minus the ATM overhead).

The ADSL framing type you should use in the UK is VC-MUX, the other option will be LLC, LLC will not work on the UK network.

In the UK the only support protocol type is PPPoA (RFC2364). None of the other protocol types available will work in the UK (including PPPoE).You must configure your device for PPPoA operation for it to work in the UK. What is an ADSL mode? Which should I use?
The ADSL mode is the type of ADSL operation you want to use, there are differences regionally, different countries and service providers use different modes. In the UK the ADSL mode is G.DMT. Most devices will auto detect this, if not you should hard set it to G.DMT.

The VPI (Virtual Path Identifier) and the VCI (Virtual Channel Identifier) are settings used to identify what channel you are using. These are ATM (Asynchronous Transfer Mode) values; don't worry too much about that for now. The important thing to know is that they should be set to 0 for the VPI and 38 for the VCI. This is the same for any ISP (Except Kingston). You will need to set these in the driver configuration of your ADSL modem or router if you don't, your ADSL device will not function properly.Note some devices will come with the correct VPI/VCI values configured, after installing the modem if it works, don't change anything.

ADSL works by using the existing phone network to carry its digital signal. This dramatically reduces the costs of deploying ADSL as no new cable needs to be laid. ADSL works at a different frequency to normal voice conversation so both can co-exist on the same wire with only a little cross over. This little cross over is why a line filter is needed, so the signals don't interfere with each other. Your ADSL modem connects to the exchange into a device called a DSLAM which splits the signals into voice (to be carried on the voice network) and data to be carried on the data network to your ISP and the Internet.DSL is distance dependant with a maximum of 5.5Km from the exchange to your house when using RADSL.

There is no difference the term is used interchangeably

Providing there are no errors on your application or any other issues at BT installations take on average seven to ten days

One thing that is very easy to forget is that ADSL is a shared service and that the speed of connectivity you have is spread across a number of other users (much like the Internet itself). So at ‘peak’ periods the speed may be slower than you expect.

One of the first bottlenecks is when the contention ratio starts kicking in. The contention ratio refers to the capacity limitations as placed by BT at their exchange while you are using ADSL. Contention is actually how much bandwidth you are sharing with a collective of other random users (ISP independent). From what we understand this bandwidth is about 17Mb/s per ‘virtual circuit’ regardless of speed and contention you are on. So the worst case scenerio at 512kb/s 50:1 you might end up with about 256kb/s download, on a 20:1 you should be unaffected. Contention really can kick in more for the higher speeds as the base bandwidth is unchanged.