Experiment 1

As we know, the ADSL splitter box has 1 input and 2 outputs, one for phone signal line, and the other for internet signal line

Plug the telecommunication line into the input. Then in the output lines, I make the swapping. I plug the phone line to the internet output, and the internet line to the phone output (See chart 1)

Then I dial the phone to call to a fax number

Surprisingly, I heard the busy tone, instead of fax tone.

Note: When I connect in normal way, plug the phone line to the phone output, and internet line to the internet output, this effect does not happen. That means I heard the fax tone as usual

Experiment 2

I make the looping back from the output to the input. To do this, I cut into the cable and heal the wire inside

Then I make the looping as seen in my attached chart 2

In a), I loop the net output to input, and connect phone output to a telephone machine. No signal at all

In b), I loop the phone output to input, and connect net output to a modem, this time I can access internet normally

Is it working correctly?