DSL + Phone Line Intercom = Disconnect

Hey folks,

I'm not entirely sure where else to ask, so if this is the wrong group I apologize.

That said, I seem to have an interesting error that I cannot troubleshoot.


1) ZyXEL Prestige 600 DSL modem. 2) Vonage Motorola MTA w/ NAT (acts as router). 3) Linksys 10/100Mps 8-port switch. 4) Radioshack Phone Line Intercom (Cat No: 43-483) 5) Radioshack DSL filters (Cat No: 279-110)

Current Configuration: I have two telephone lines at my house: Line A and Line B.

Line A is our main "voice" line and has the intercoms connected to it.

Line B is our "fax" line, has the DSL installed on it, and has appropriate DSL filters for the fax machine and the one telephone connected to it. Obviously, there is no filter on the jack connecting to the DSL modem.

Lines A and B both terminate at the same jack (using red/green and yellow/black pairs) where the DSL modem is located. Previously, they were both wired into the same actual socket and were split using a standard two-line splitter.

Problem: Even though the DSL and intercoms are connected on two physically different lines, whenever the intercoms are used they disconnect the DSL (requiring about 30-60 seconds until the connection is reestablished).

Steps Done To Correct This Problem:

1) Install DSL filters on Line A (I considered this to be unnecessary and expensive, but did it anyway). This has resulted in the intercoms being completely unusable. Evidently the filters also filter out the intercom signals. 2) Remove the two-line/single-socket jack described above and replaced it with a two-line/two-socket jack with both lines on red/green of their respective pairs. Line tests indicate that both lines are wired properly. Line A gets signal and the intercoms work. Line B gets DSL service. Unfortunately, when the intercoms are used they continue to interrupt the DSL service.

Conclusion: I have been unable to rectify this situation and am thoroughly puzzled. The only thing that I can imagine causing this is induction between the two lines; thus signals from the intercoms are inducing current in Line B, causing the DSL to disconnect. I can see of no way that I can fix this problem, short of replacing all the straight-wire phone lines in my house with twisted-pair Cat5...which is not really an option due to the amount of wiring here. :/

Any advice? Cheers!

Reply to
Pete Stephenson
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