Say you have two phone jacks in your house. One (A) just has a phone going to it, and it has a wall-mounted DSL filter. The other (B) gets split at the jack. One end of the split (B1) is plugged into a filter and then a phone. The other end (B2) gets split again; one end (B2a) goes directly to the DSL modem, no filter, and the other (B2b) goes into a filter, into an answering machine, and then directly into a phone.
Is there anything about this setup that needs another filter (answering machine to phone?), or fewer splits (we could ditch B1 without too much trouble)? Could this setup account for our getting 100% of our advertised bandwidth up, but only about 10% of our bandwidth down?
(I'll probably end up crawling around on the floor disconnecting things and rebooting the modem—oh, and we have a wireless router too—tonight anyway, but that's tedious and if anyone can assure me whether it's definitely a complete waste of time, that would be nice. Next step, of course, is to contact Verizon. (Oh joy.))