i haz teh awsum
Follow-up to this post...
I don't know if the unfiltered kitchen phone is interfering with the DSL connection, but the DSL connection is certainly making it unpleasant to use the kitchen phone. It occurred to me today, there's a hole in the drywall behind the phone now... maybe I could put one of those fancy new DSL filters behind the wall rather than between the wall and the phone. So after dinner I got out the shovels and rakes and implements of destruction and took the phone off the wall again. Not enough room... but that lath was almost sawn through already (by accident, in the previous episode), why not finish the job? So I did that, and now have a hole in the drywall that opens into about a four-inch-deep-by-several-feet-wide-and-high space between walls. Plenty of room for the DSL filter.
Of course, the DSL filter has a modular jack at both ends (one male, one female), and the wire coming up between the walls is just wires. For that matter, the wall plate to which the phone attaches has a modular jack on the front, but just wires on the back. So I cut the tail of the DSL filter in half, stripped the insulation from the ends of the wires in both halves, plugged the male end of the tail into the female end of the filter, and had a DSL filter with bare wires at both ends instead of modular jacks at both ends. Twisted the wires on one end together with the wires coming up between the walls; twisted the wires on the other end together with the wires on the back of the wall plate; covered everything with electrical tape (which has a disturbing tendency to fall off), and tested the connection with a more ordinary phone. Clear dial tone, no DSL hiss. Yay! Screwed the wall plate back into the wall, mounted the kitchen phone onto it, and tested again. Clear dial tone, no DSL hiss. Yay!
The result is a kludge that will no doubt amuse the next person who opens up that wall, a decade or two from now: the telephone line has a twisted-wire connection to a 2-inch cord that goes into a DSL filter that has a modular connection to another 2-inch cord that has a twisted-wire connection to a wall plate that has a modular connection to the phone. But it seems to work.
Next telephone challenge: the satellite-TV guy is scheduled to arrive on Sunday to install a satellite dish and one or two receiver/decoder thingies (one in the living room, where the main TV is, and one in the attic, where there's a surplus TV that we never use but might if we got the attic clean enough to use as a sewing room). For reasons I don't entirely understand, the receiver/decoder thingies have to be connected to a phone line. (Among other things, they use this for "loss prevention": they periodically check remotely that each receiver/decoder thingie is connected to the phone number it's supposed to be connected to, and if it's connected to the wrong phone number, they disable it and come knocking on your door.) There is AFAIK no phone jack anywhere in our dining room or living room, and the nearest phone cord AFAIK is the one in the kitchen with the aforementioned kludges on it. There might be a phone jack in the dining room wall, but the most likely place for it is behind a 7'-tall, 12'-long wall unit that's currently full of books, glassware, china, and other heavy stuff that I don't want to move on the off chance of finding a phone jack behind it. I guess we'll discuss this with installation-guy when (s)he arrives.
I don't know if the unfiltered kitchen phone is interfering with the DSL connection, but the DSL connection is certainly making it unpleasant to use the kitchen phone. It occurred to me today, there's a hole in the drywall behind the phone now... maybe I could put one of those fancy new DSL filters behind the wall rather than between the wall and the phone. So after dinner I got out the shovels and rakes and implements of destruction and took the phone off the wall again. Not enough room... but that lath was almost sawn through already (by accident, in the previous episode), why not finish the job? So I did that, and now have a hole in the drywall that opens into about a four-inch-deep-by-several-feet-wide-and-high space between walls. Plenty of room for the DSL filter.
Of course, the DSL filter has a modular jack at both ends (one male, one female), and the wire coming up between the walls is just wires. For that matter, the wall plate to which the phone attaches has a modular jack on the front, but just wires on the back. So I cut the tail of the DSL filter in half, stripped the insulation from the ends of the wires in both halves, plugged the male end of the tail into the female end of the filter, and had a DSL filter with bare wires at both ends instead of modular jacks at both ends. Twisted the wires on one end together with the wires coming up between the walls; twisted the wires on the other end together with the wires on the back of the wall plate; covered everything with electrical tape (which has a disturbing tendency to fall off), and tested the connection with a more ordinary phone. Clear dial tone, no DSL hiss. Yay! Screwed the wall plate back into the wall, mounted the kitchen phone onto it, and tested again. Clear dial tone, no DSL hiss. Yay!
The result is a kludge that will no doubt amuse the next person who opens up that wall, a decade or two from now: the telephone line has a twisted-wire connection to a 2-inch cord that goes into a DSL filter that has a modular connection to another 2-inch cord that has a twisted-wire connection to a wall plate that has a modular connection to the phone. But it seems to work.
Next telephone challenge: the satellite-TV guy is scheduled to arrive on Sunday to install a satellite dish and one or two receiver/decoder thingies (one in the living room, where the main TV is, and one in the attic, where there's a surplus TV that we never use but might if we got the attic clean enough to use as a sewing room). For reasons I don't entirely understand, the receiver/decoder thingies have to be connected to a phone line. (Among other things, they use this for "loss prevention": they periodically check remotely that each receiver/decoder thingie is connected to the phone number it's supposed to be connected to, and if it's connected to the wrong phone number, they disable it and come knocking on your door.) There is AFAIK no phone jack anywhere in our dining room or living room, and the nearest phone cord AFAIK is the one in the kitchen with the aforementioned kludges on it. There might be a phone jack in the dining room wall, but the most likely place for it is behind a 7'-tall, 12'-long wall unit that's currently full of books, glassware, china, and other heavy stuff that I don't want to move on the off chance of finding a phone jack behind it. I guess we'll discuss this with installation-guy when (s)he arrives.

no subject
Yes, that was my impression. Obviously, they don't bend over backwards to tell you that you have that option, but there was some comment in a footnote on a scrap of paper in the bottom of locked filing cabinet in a basement room labeled "Beware of Cougar" that suggested that the phone connection wasn't strictly necessary.