TV in tokyo

I just bought a TV and most of my friends said they didn't sign up for anything, they just plugged the cable in the wall and had basic TV channels. But I will get channels that play okay for like an hour than they chip out and dont play at all for a few days. Is this something wrong or is it some kind of trial thing by the TV networks that I have to sign up view them properly. And if so does anyone know how to go about doing that?

K,

It all depends on where that socket in the wall leads to...
If it leads to an aerial on the roof - shared or otherwise - there shouldn't be any problem receiving the basic set of terrestrial channels.
If the TV signal is supplied by a cable service, then you will probably have to contact them and pay a small monthly fee to watch even the basic channels.
There is also the possibility that your TV set is simply defective.