I'm using an inline DSL filter as an extender for the phone jack on my laptop. That is, rather than frequently plugging and unplugging the phone line to/from my laptop, I plug and unplug to/from a DSL filter connected to the laptop. I do this because it's much easier to replace the filter/extender rather than fix any problems on the laptop due to wear and tear.
I am not making use of the filter functionality, only it's ability to physically extend the jack by a small distance. I can do the same for about 14 bucks by purchasing a 6-inch length of phone cable (male plugs on both ends) and a female-to-female adapter. The important thing is that the 56Kbps dialup signalling is preserved in both directions, /and/ the laptop's modem is not unduly stressed or damaged. I am assuming that this occupies the normal voice spectrum (upto about 3.5KHz).
In order to use the DSL filter instead, the filter must be used "backward" i.e. with the mail end plugged into the laptop (it should plug into the wall), and the female end connected to a phone cord that plugs into the wall. I'm not sure if that is OK. For one thing, I'm not sure if the filter is made of entirely passive, linear components. A simple concept circuit at
What a Microfilter does* ------------------------ A microfilter performs two main tasks. First, it prevents high frequency noise from appearing at the telephone and potentially decreasing voice quality. Second, it prevents the telephone equipment from interfering with the modem by preventing harmonics, overtones and changes in impedance caused by the telephone equipment.
*FromI wonder if those with experience in circuitry for interfacing to telephone lines can comment on the risk of this approach (long term risk to the laptop, that is).
Thanks,
Fred