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Line test?


Line test?

I'm one of the people currently experiencing random loss of connection since upgrading from 512 to 2mb and have a BT engineer calling tomorrow.

BUT i've just plugged in my old 56k dialup and connected to BT Click (at 4p per minute!!) and it works fine with no disconnection.

Does this mean that the line is OK or is it possible that the line might cope ok with 56k and even 512 but not 2mb?

If they find that the line is OK I'll get charged I believe.

Community Veteran
Posts: 6,983
Thanks: 8
Registered: 10-04-2007

Re: Line test?

Does this mean that the line is OK or is it possible that the line might cope ok with 56k and even 512 but not 2mb?

The line is probably fine for the lower frequencies that dial up uses but the higher bit rate services ADSL 512K 1M and 2M are more demanding.

Any noise or additional loss on the line will have a much greater effect on a 2M ADSL than it would on a 512K connection.
Community Veteran
Posts: 14,469
Registered: 30-07-2007

Line test?

Your modem is effectively using the same frequency bands as a normal voice phone so if your normal phone is working fine then a modem will as well. ADSL uses a much higher frequency band (above the normal voice frequencies) and as such will be effected by noise at the higher frequencies. Also the higher your ADSL speed, the bigger the frequency range used and the more likely noise will effect the connection.

Line test?

hmm ........ so my thoughts so far:

not the pc - it worked fine before upgrade and works fine on the 56k.

modem? - worked fine before upgrade.

Plusnet? - they tell me it is all fine their end but it was fine before upgrade but not now.

BT line? - worked fine before upgrade but not now. works fine with 56 & 512k.

Line test?

There are distinct differance between 512Kb and 2Mb, that means the "fine before the upgrade" invalid.

The only truth in that is that before, it worked, and now it doesn't.

2Mb uses a much wider spectrum of frequencies on yoru phone line. These are frequencies that where not used during the 512Kb line.

If there is a fault with one, ADSL is designed to switch to another, so that service is maintained.

However, as 2Mb uses more of them, there are less of these spare freqencies (known as bins) available for the line to drop back onto.

If it runs out of spare, you get the inability to use the service, as you have now.

Think of it this way. You have a truck with 2000 buckets, 700 have holes in them.

You need to transport 512 gallons of water, so you fill 512 buckets with 1 gallon each. You have more than enough spare without holes.

However, when you change and need to transport 200 gallons, you can't, as 700 have holes in. Not enough spare.

In much the same way you coudl argue the quality of the buckets, when ti comes to ADSL, you argue the quality of the line.

Hope this helps understand why because a 512Kb service works, it doesn't mean 2Mb will.