ON att if i use my cell fone to make a 3 way call/conference does it cost money?

I have a 2 year contract.
fyi
like besides the regular free.
if it after 9 pm 4 me its free

You would be using whatever minutes you were in. So if you were using daytime minutes you would be using double the minutes. Same thing applies for nights and weekends. or mobile to mobile. The only difference would be if you were talking to an AT&T cell phone on one line, and any other service on the other line. Then ONE phone would be using Mobile 2 Mobile, then the other would be using daytime or night time minutes.