Data over Telephone Line

Hi everyone…i was wondering if it is possible to send data(such us a string)over the telephone line without interapt the actual phone and calls??? :-?

After some research i found that a small circuit it might be needed than connecting an arduino pin directly to the phone line.

Sorry for bad english… :-[

are you trying to do this on lines connected to the network? you may want to re think that, its illegal in many places

otherwise you need a modem to make a call, or its just wire if its not connected to the network

the whole house is connected to a network but i just want to send data from one room to the other using the house telephone connection

If the whole house is networked, why bother with using the phone line? :-?

because i want to control an led matrix…and i just wondering if it is possible w/o using the house network

a normal phone uses just 2 lines.
in most installations in houses (here in dk anyway) the lines in the house will have 4 lines.

so in theory, you could use the free line pair to your arduino comms.

just make abolutely sure that the lines you use are not connected to thee phone lines. (its illegal in many places, as mentioned before).

also: if you do use the phone line in use, be aware that there may be up to 48 v on the line while idle - that will fry your arduino without the right circuitry.


you can do so its just got to be setup where it does not interfere with the rest of the phone network, I doubt your local telco would appreciate you much if every time you blink a led you knock out DSL service for a quarter of your city

but also spumanti does have a good point, there is usually 2 pair in household wiring, and unless you have 2 lines 1 pair should be dead, so I would look at how things are actually wired to start with

i know that…but however when i tried(with voltage protection) to send something it didnt work and it was like i had forget the telephone open

in my house there is one pair of cables…except from the kitcen plug that has 2 pairs…

in my house there is one pair of cables

Then you pretty much can’t do it without being rather illegal.

can some1 explain me why this is illegal(i have to make a research if that is the same for my country GR)

adding signals onto a network you dont own can cause all sorts of problems, it can interfere with telephone communications outside of your house, it can hose dsl lines, if you can isolate it where its only in your house then you should be ok until you need to have a service man come out

but once you do all of that you would be in a pile of electronics, something like wireless would be much more practical

ok thanks all of you for your fast replies…have a nice day