Exchange Only Line

OK. This one has me baffled. What precisely is the issue with an 'exchange only' line when the customer is C. 100ft from the exchange. I completely understand that an exchange only line is one that doesn't go via a cabinet and this might be an issue if the exchange was many miles away, but no one has ever explained (BT least of all) why a telephone line connected to the very epicentre of the local wired communications network a few feet away should be a problem when it comes to getting it hooked up to fibre. Surely, it's the easiest of all places to make such a connection?

No half baked answers, whinging arguments or plain guess work please. I need to be able to convey this to someone else. Just a clear and concise explaination why not being connected via a cabinet is a problem. No BT type, obfuscated answers suggesting I speak to Boris Johnson for political intervention or the Pope for spiritual intervention either. Is this a technological issue? (I do not believe this), Is this a kafkaesque regulatory one? (this I can believe) Or just plain lack of will by all parties concerned?

In reply to a post by Desmond:

What precisely is the issue with an 'exchange only' line when the customer is C. 100ft from the exchange.

Put simply the "fibre" services are delivered to you as Very high speed Digital Subscriber Line (VDSL) services. This requires a VDSL DSLAM at the other end of your phone line. For ADSL this DSLAM is in the exchange, for VDSL this DSLAM is in a second cabinet that is connected to the line at the first cabinet.

BT can't install a VDSL DSLAM inside the exchange for your line as this would put too much power onto the line and affect the other customers on older ADSL products (BT customers, TalkTalk customers and Sky customers, and any other LLU provider such as Zen).

All ISPs operate under an industry agreement (with Ofcom) called the Access Network Frequency Plan (ANFP) which is what limits this.

In some areas (with enough exchange only lines) BT openreach have basically cut the wires outside the exchange and installed a cabinet, often in the street close to the exchange. Then here they can fit a FTTC cabinet twin. Don't hold out your hope for this.

If you're that close, you should be able to get 20meg download and 2.5meg upload already on ADSL with Annex M ?

An excellent explanation James .

Nope! None of that makes sense. You failed at "too much power onto the line".

Feel free to try again!

In reply to a post by Desmond:

Nope! None of that makes sense. You failed at "too much power onto the line".

BT can't because of good technical and mathematically provable items that are complex to explain.

DSL is essentially a radio signal onto the wire. If you've ever done any amateur radio, or CB, then you'll know about transmitter power and antenna efficiency. If not, there are probably lots of good Wikipedia articles.

In reply to a post by jchamier:

BT can't install a VDSL DSLAM inside the exchange for your line as this would put too much power onto the line...

Also, there may not be enough space.

In reply to a post by RobertoS:

An excellent explanation James .

Thanks! Its still a very technical topic, and I'm nowhere near an expert. Just a constantly learning amateur.

Easest version: there is a rule saying they cannot do vdsl from inside exchange

So. What you are saying that if the line in question went 95ft to a cabinet outside the exchange you can get it connected to VDSL. However, if it goes another foot to inside the exchange it can't be connected to VDSL? Maybe this is becuae there is some strange Anti-VDSL field that exists on the other side of an exchange outside wall, but does not exist anywhere else in the universe? This field mysteriously causes huge amounts of 'power' to accumulate as your line passes throught the exchange wall that will affect other people, who are not connected to your telephone line at all.

I have a word for saying all that, but I can't use it.

Thank you Saffy. I was hoping you might answer. So, the simplest answer is that for regulatory reasons mere mortals need to be connected to a cabinet to get fibre. All this is because of chinese walls and kafkaesque regulation? Yes?