Slow speeds and no master socket

Hi,
I have an ADSL speed of 500-600kbps which not uncommonly loses sync.
I wanted to try and use an i-plate to improve the line but I cannot find my master socket - all the sockets in the house are un-branded and indentical.

The house was built in 2008 and outside there is a small grey BT openreach box. On the other side of the wall is a socket but it doesnt have any of the 'usual' master socket features - no obvious input and then extension output points just one phone cable coming in. None of the other sockets seem to be masters either (have removed them all to look at cabling.

Are modern houses phone lines wired differently to the traditional master socket design?
Is there any way to isolate the DSL signal at the grey box to improve line quality by isolating it from the rest of the extension wiring?
Thanks

...or alternatively, try and work out which socket the outside cable comes too first?

Newer houses dont have a master socket per se. The box on the outside of the house is the master socket.

http://www.kitz.co.uk/adsl/btsockets.htm

scroll down to 'external nte' is that what you have?

Thats the one!
Is there any way of working out which socket the cable goes to first?
Tried the nearest one but bizarrely can disconnect but all the other sockets stil have dial tones

Is there just two wires connected as in the photo http://www.kitz.co.uk/adsl/images/phone/external_NTE...

If lots of them, then a clear photo may help explain better than words.

Knowing your ADSL lines attenuation i.e. stats from your router will help.

if it is showing attenuation of 63dB and the phones work, then very likely your are a long way from the exchange and thus other than stopping it disconnecting you might not get more speed.

Line stats:
Data Rate
Stream Type Actual Data Rate
Up Stream 448 (Kbps.)
Down Stream 2016 (Kbps.)

Upstream Downstream
Noise Margin 19 dB 6 dB
Attenuation 61 dB 50 dB

Actual speed is about 900kbps

The NTE external box has one wire coming into it from a duct in the ground and one wire coming out into the house - looks like a normal thin telephone cable rather than a bundle of lots of them - looks pretty much the same as that picture

thanks
squelch41