DSL modem on a split phone line with filter

[marko]

I've been noticing that my 3Mbit/768Kbit DSL line (verizon) has been constantly dropping and going back up. A while back I was getting more answering machine messages at home so I moved my answering machine from the main floor of the house to my basement office. The phone port I put the machine on also has a dsl modem and another phone on it.
So I used a Y splitter to send one side to the dsl modem and the other to the dsl filter, answering machine and phone.

                            / dsl modem -- lan
phone jack | ---(splitter)/ 
                           \
                            \ dsl filter -- ans machine -- phone

Sometime after that all this flaky DSL behavior started. So on a whim I unplugged the dsl filter/answering machine/phone. At this point the dsl modem was the only thing on the line. At this point it got more stable.

Is there an electrical reason for this, like is it bad to have a DSL filter plugged into the same jack as used by the modem? Note that the filter is not upstream of the modem (in that case it wouldn't work at all) but just nearby. I'm thinking there might be some kind of reflection off the filter that's adding noise to the line? My other phones then might not be a problem because they and their associated filters are upstairs and far enough away to not cause a problem.

[DBelton]

Splitters are notorious for being bad news on a DSL line. Most of the splitters you buy are good (somewhat) for voice, but crappy for data. So I would suggest you start looking for the problem by checking out the splitter.

If you really need a splitter in there, get you 2 good jacks and just wire them up instead of using a splitter. You could also get the double jack that replaces the single in the wall box.

AT&T includes a filter in their package that has a filtered output and also an unfiltered output that you plug your modem in to. While not really the best solution, you could go that route as well.

The best solution is what I have done here.

You put your splitter/filter in the NIB where the phone companies line comes into your house. Then you don't need any filters on your phones, and run a dedicated "home" line from the NIB to your DSL modem.

[marko]

Originally Posted by DBelton

You put your splitter/filter in the NIB where the phone companies line comes into your house. Then you don't need any filters on your phones, and run a dedicated "home" line from the NIB to your DSL modem.

The way my basement is furnished makes the ideal way difficult because putting a filter in the NIB would require another RJ11 cable to be wired from the NIB to the DSL capable wall jack. I'd have to have someone cut into my drywall for that.

I think I'll just move the phone and ans. machine to somewhere else and just have the modem there.

[DBelton]

Well, if you do need the phone/answering machine there, then invest in a good quality splitter, or replace the single jack with a double and wire them both for the same line. Put your DSL modem on one, then your filter/answering machine, etc.. on the other. You wouldn't have to run another cable for that.

[marko]

I don't need it there, it was just a bit more convenient ... any way, my job search is over so I won't be getting so many calls a day anyway