@jimp: Yeah but unless those devices do something other than split the wire pairs into two groups, it could be a mix of those devices, split jacks, or some other wacky implementation. Either way, it's worth tracking them all down and eliminating them. My guess is that it was put in to save money and I probably won't be able to get rid of them unless they spend money on additional cabling. @phil.davis: You could even do ADSL data plus voice on a single copper phone line, but I digress  :P In UK we get this quite often with our ADSL lines. I remember my internet getting cut off sometimes when the phone rings. edit: Going to lock topic as it is getting too long and off topic now.