Frequently Asked Questions General ADSL * What is ADSL? ADSL (Asymmetric Digital Subscriber Line) is a broadband (fast) internet access technology. ADSL allows very cost effective, always on high speed internet access. The Asymmetric part means that ADSL is much faster downloading than uploading. This asymmetric nature makes it perfect for the home user who will usually only require very fast download speeds. * How does ADSL work? 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. * What is RADSL? RADSL (Rate-Adaptive Asymmetric Digital Subscriber Line) is an evolution of ADSL that allows the range of ADSL to be extended from 3Km to 5.5Km allowing a far greater reach of customers. RADSL adapts to poor signal quality, this can sometimes result in poor upstream speeds though. * Can I get ADSL? ADSL is available to anyone with a BT phone line who lives within 5.5Km of a ADSL enabled exchange (this is 5.5Km cable length, not as the crow flies). ADSL is also not compatible with ISDN or any other services so if you have these on your line they will not work either. Line quality is another issue, if you have very poor line quality, you may also fail the activation test. To check whether you are on an ADSL enabled exchange click here and enter your phone number. * I want the fastest products possible, which is fastest? All the products provided by DSL-Warehouse are rated upto 8Mbps downstream and varying from 640Kbps to 1Mbps upstream. This does not mean you will get this speed as the speed you get is determined by the service you buy from your ISP. When considering which hardware to buy the speed is determined by the type of connection, although it should be remembered that the difference is marginal as the real bottleneck is in the DSL connection, but for those who want to squeeze a millisecond or two out of there response times the fastest are the Ethernet routers, followed by PCI modem and then USB modems. General Installation * What is a VPI & a VCI, do I need to set this anywhere? 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 38 for the VCI and 0 for the VPI. 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. * What protocol type do I need to use? 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. * What framing type should I use? 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. * Can I Increase the speed of my ADSL connection, my modem says it will run at 8Mbps? No, you cannot change the speed of your connection at your end; this is controlled by your ISP. You can only increase the speed by buying a faster service. Most modems are capable of running ADSL at 8Mbps; most home services in the UK are capped at 512Kbps. * I bought a 512Kbps service but it says it connects at 576Kbps why? 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). Microfilters * How many Microfilters do I need? A Microfilter is needed for each socket in use on the phone number activated for ADSL. As an example if you have three sockets in your house, one in the study where your PC and phone are, one in the bedroom for a phone and a third in the lounge unused. You would need two filters, one for the study for the ADSL connection and the phone and another for the phone in the bedroom. If a set top box was to be added in the lounge for digital TV another filter would be required there. * What is the difference between a Microfilter and splitter? There is no difference the term is used interchangeably * What does a Microfilter do? A Microfilter filters out the ADSL signal from the normal phone signal, allowing you to use both on the same line; it also provides two sockets, one for ADSL and one for the phone/fax/answering machine/set top box. * What devices need to be filtered? All phone devices need to be filtered when ADSL is used on your line, including: o Normal handsets o Cordless handset base stations o Fax machines o Answering machines o Set top boxes * What is a BT approved Microfilter, do I need one? Not all Microfilters are BT approved, non BT approved filters will work although BT will not support there use, this could cause problems with diagnosing your ADSL service if it is not working as BT will instruct you to get BT approved filters. DSL-Warehouse recommend BT approved filters but give you the option of much cheaper no BT approved ones. * What is the difference between a passive and an active Microfilter? 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. * If I only use my line for ADSL, do I still need a filter?