In addition to the various blog and forum posts we have dealing with speed faults and other ADSL issues I thought I'd add one to help those that may be experiencing problems with ADSL synchronisation - hopefully this will explain a few things and also dispel a few myths as well. The ADSL signal itself is generated at the exchange, at the DSLAM (for those that want to know, this is the Digital Subscriber Line Access Multiplexer) and then transmitted down your phone line to your modem or router. As such any fault with synchronisation will be caused by something either at the exchange, something affecting the wires between the exchange and your premises, a fault in the master socket or the modem/router. There are other possibilities but they can be bracketed in with the above. Exchange Fault This is usually an issue with the jumpering (this is where the wires carrying the ADSL signal are connected to your phone line) though it could also be a faulty DSLAM or line card. There aren't any tests that either the end user or ourselves can do to prove this, though sometimes we will get an error on our line test tool that would point to a fault. One of the most annoying situations I have come across is when this tool reports that the end user's modem is in sync even though we know it is not. This can lead to extended fault resolution times due to our faults team needing to explain to the BT wholesale diagnostics team that in spite of their test tool reporting that everything is fine a no sync fault is still present. External Wiring Fault These can be easy to diagnose (for example if a tree has fallen on the wires) provided the break in the wiring is easy to see. If the wire is actually broken this is also usually picked up by line tests. It gets more difficult with issues such as wires that are partially broken, i.e. when the line flexes in the wind or even worse if there is an exposed section of wire (or hole in a green box or other junction point) that is affected by moisture, especially if this is only apparent during bad weather. Otherwise it may well be simply that the line is too long to support the service, or there are other issues – these can include underground faults (usually costly to repair), lengths of aluminium or fibre optics – in these cases it may be too expensive for BT to replace the relevant sections of line, possibly even the whole line itself. In this case BT will consider a refund for the service – a full refund, if the service has never worked since installation (this is called an early life failure, and will be dealt with in a future blog post) or a refund from the time the fault was reported, if the service was working prior to the fault. Internal Wiring Fault This is easy to eliminate (within reason... if it's a fault in the master socket it will require a visit from a BT engineer to resolve) and must be before a fault can be escalated to BT simply because BT do not guarantee any internal wiring. Provided you test the connection from the master socket and unplug all other items from the line (including faxes and Sky boxes) internal wiring should be eliminated from the equation. As testing the connection from the master socket will also remove almost all possible sources of interference from your internal circuit, if the fault is still apparent you have proved that the fault does lie within BTs realm of responsibility. Frequently in this case BT will send out an engineer who will fit an SSFP (service specific front plate) with a built in microfilter. This fixes most issues with interference on internal wiring/equipment but does mean that you will need to plug your ADSL equipment into the master socket as all extension sockets are filtered by design by the SSFP. Electrical Interference This is usually an intermittent issue, frequently occurring at similar times each day. Frequent culprits are street lighting and especially (when 'tis the season) Christmas tree lights – basically any electrical equipment does create RF interference. This can, if powerful enough, break up the ADSL signal as it travels down the phone wire. This interference - if the cause of the fault - may well be something in your own premises, though once BT ascertain that this could be the cause of the fault they will arrange a visit from an SFI (specialist faults investigation) engineer who will search for signs of interference. The delay if this is the case can come in several flavours. It could be that the owner of the faulty equipment is reluctant to replace this, or that a request needs to be the council to work on any affected street lights, or any of a whole plethora of other reasons. I think my favourite was the farmer whose phone line was routed over an electric fence, and every time his sheep brushed the fence his broadband would drop. Either that, or the user whose broadband would drop between 12 and 2 daily, except on Sundays – this turned out to be the chippy below him cooking pies (the microwave was faulty). Faulty Router/Modem or wiring issue This is another fairly common issue that should be picked up by ourselves when we are informed of a fault. Ideally we would prefer that alternative hardware is tested prior to raising a fault but if not then certainly prior to arranging an engineer visit – as such we may be able to arrange for a router to be sent out to the customer to test if they have no alternative available. However we would also ask that you bear in mind you can also test your own hardware on another known working line – if the fault is still apparent with the hardware connected to a different phone line then it is likely to be a faulty modem or router. There are other faults that can occur but I hope this has explained the reasoning behind some of the tests we request in order that we can report a fault. It is understood that a lot of these are inconvenient, given the location of the master socket in some houses and that some people may be unable to move a large desktop PC and modem up into the loft/down into the hall or wherever. We will do our best to help out in these situations, but given the costs involved (BT have a standard charge of £144 + vat that is issued if a fault is found to be with the customers' equipment or internal wiring) we hope you appreciate the importance of, and now the reasons behind, these tests.