Accessing only one FXO line for dialing out

Hey guys, I’ve just put a new Asterisk/freepbx 1.8 one line. Seems to be working well except for dialing out of this guy. I have (3) FXO ports all with Dial tone. when the first person makes a call no one else seems to be able to seize one of the other line to make a call. I must have an issue with the out bound route. Anyone have an idea where I might be going wrong here? Thank you!

There is a concept of a trunk group, normally the default group is incorrectly lowest to highest for outbound, to avoid glare build and use G0 not g0 (highest to lowest) as your trunk, or perhaps more prosaically plug your co lines in backwards, then make sure you make your outbound calls uingthe trunk and not the individual line.