Broadband enabled telephone line query

  CurlyWhirly 19:31 21 Oct 2005

I have just seen someone mention that on a broadband enabled line, the dial-up speed is only around 28k which is around half the speed of a 'normal' dial-up connection.
I always thought that broadband and dial-up were seperate technologies so I am just curious as to *why* this happens?

Could it be that by lessening the maximum dial-up speed, more bandwidth can be given to broadband?
I have *no* intention of going back to dial-up by the way (perish the thought).

  Chegs ® 20:26 21 Oct 2005

I'm only guessing(aided by a google search)but I think its due to the BB signal affects what the dialup modem see's.Eg,the BB signal is seen as noise by the dialup,result of a noisy line on dialup is slower speeds.

  bemuzed 20:50 21 Oct 2005

Chegs - sounds reasonable to me. When you use a dial-up modem teh signals are sent in the frequency band used ofr vocie transmission. With Broadband the ADSL signals are sent at a higher frequency, and as you say i guess they interfer. incidentally, the copper wires were only installed to support vocie, and it is fortuuitous they support ADSL frequencises. Sometomes they don't and the user cannot get Broadband.

  CurlyWhirly 20:55 21 Oct 2005

Chegs ® - Your reply sounds very reasonable to me ;0)

bemuzed - I agree as it is *very* good news that copper wiring supports ADSL frequencies.

  Jackcoms 22:11 21 Oct 2005

Don't quite follow this.

Surely, the dial-up signal uses the same low frequency part of the line as your 'phone and, if the line is properly ADSL filtered, there should be no noise and, thus, no drop in dial-up speed?

  Chegs ® 22:39 21 Oct 2005

True Jackcoms, but unfortunately it does affect dialup. In the email I received when 1st signing up for ADSL (several years back now) it stated that I would experience a slowdown of dialup services(which were offered for when my ADSL was broke)There was also issues with using a fax machine on ADSL,I presume for the same reasons of ADSL noise. The majority of filters sold for ADSL services are extremely basic, barely able to actually do the job due to cheapo components used.

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