give him fish.- Hide quoted text -
I use broadband from the cable TV company and don't really know much about DSL. Telephone cables don't carry as wide a frequency range as TV cables so I'm not sure how the data is multiplexed with the audio.
How "active" are the splitters? I suspect they might filter the audio from the data line and vice versa. At the worst it would degrade the data signal when that phone is used, between the router and the Internet provider leading to more retransmission of bad data blocks.