Landline Prank

[ravenmaddox]

I have this buddy that lives in the sticks and STILL uses a dial-up internet account (I'm really surprised it is still an option) but it gave me an idea of a prank. I want to build some kind of resister / device that I could plug into one of his phone jacks and it would allow him to make and receive voice calls but would make data transfer over the line impossible. Any ideas?

[markov]

At first I was thinking about those DSL line filters that you plugin for jacks where you want to use the phone only, but that shouldn't work because a phone modem isn't like a DSL modem..

Not sure how you'd accomplish this without putting quite a lot of work into designing a filter

[rbcp]

Maybe something that detects really loud noise and activates a relay switch, bridging the two phone wires together until the noise stops.  Seems like this would be easy to build and is probably something available in those electronics kits for kids.

You could order call waiting on his data line, then ring his phone whenever you know he's online.

[ravenmaddox]

Now I'm thinking along the lines of how car audio amplifiers filter high-pass/low-pass that maybe I could do something like that to filter out a certain frequency integral for modem operation but wouldn't be noticed during voice. I only remember a little of my high school electronics class but I don't think it would be too hard to design a circuit once I decided on the frequency to remove. Of course that would prolly have to be inline with the modem and your idea now seems much, much simplier RBCP.

My original thought was more of a phone plug with either a resister or capacitor between the two wires. I once built a phone tap that allowed a headphone jack to be plugged into the phone line, but by itself it cause a little static which might be enough. Or the old black-box designs that never really worked might be enough.

Now that I'm thinking.. didn't Think Geek sell some kind of "annoy-er" like this some years ago?