If I find a apartment or a house, and there are no telephone,

then I should install new telephone line by myself.

in this case, how many days must i wait for new telephone line?

and Which telephone is better, TT&T or TOT?

Depends where you want to stay I guess. The two lines I have had installed took 3 days and 1 week. Paid about 2000 BHT.

u waited only 10 days to get telephone line?

and why so cheap 2000 baht?

because TOT telephone cost 3500 baht for new instalation

call them up I would suggest. So many questions which wouldnt be needed if you come here and sort things out yourselve