First time on here. I thought i would share the following with you.
Just recently went live with a Phone and Broadband package from a well known Communications Provider. The phone side no problem, clear as a bell.
The ADSL side mainly non existent or when the router manage to find the sync signal managed around 300kbs tops. My house is around 1.5 miles from the exchange but got down stream attenuations of 80db. S/N ratios were pretty low too.
Being reasonably clued up technically i carried out all my investigations within the house right up to the test socket on the NTE5A box with still the same results.
Having to run the gauntlet of the 1st and 2nd line technical departments (Indian call centres) and a visit of the CP's own engineer, the problem was no nearer being resolved. Next stage was to actually be able to speak to a 3rd level engineer in the UK, what a welcoming experience. He arranged to have a BT Open reach engineer visit the house hoping that the ball lay squarely in their court and not being hit for £130.
BT Openreach engineer arrived and within two minutes found the problem, luckily on their side. This was an illusive one. The drop wire was terminated (Screw terminal block) in a white BT junction box which also had two encupsulated towers which appeared to me to be anchoring posts of some sort as the orange and white wires were wrapped around them. From the junction box (IDCs) another wire was connected to a BT Openreach NTE5A box.
The two so called anchoring towers in the BT junction box turned out to be RFI chokes (Inductors to suppress radio interference) one in each of the A and B wire circuits. Living in North London, there was time that Capital Radio was being picked up on telephone circuits amongst other audio devices, as their AM transmitter was very powerful and was sited a few miles away. It was these RFI chokes that was attenuating the ADSL signal.
Following their removal and a straight through connection made, the engineer measured an increased ADSL speed of around 5Mbs. These components were not detectable by the various diagnostic tests carried out by my CP or from the exchange. The telephone line also had a DACS (Digital Access Carrier System) unit fitted at one time which i had to get BT to remove some years ago when i had dial up internet. I had initially thought BT had put it back on again, due to lack of spare twisted pairs in the area, which was killing my ADSL signal.
These BT junction boxes fitted with RFI chokes/devices may well be still existing in various locations in many properties including roof spaces out of sight out of mind.
Just another factor to consider amongst all the others when dealing with ADSL speeds.
Legally it is up to BT Openreach to remove these and effect a straight through connection to the NTE5A box but even if one is aware of these try explaining this situation to a call center operative 5000 miles away.