In short, no. No one calls for friendly fire nor warns about it. We just take steps to avoid it.
Your guy on the ground will call for fire and identify a strike target. HE will advise targets are danger-close.
He knows to make himself small so no one is even going to mention friendly fire.
Direct radio between your guy on the ground and the strike aircraft is pretty unlikely but he IS likely to communicate directly with indirect fire-support thus (use your own call-signs and details:)
Artillery this is Infantry. Fire for effect over
Infantry this is artillery. Fire for effect out
target location (grid coordinate polar coordinate etc). over (if this is not PRECISELY known, the initial call will be to adjust fire, not fire for effect)
target location out.
16 troops in the open danger close over
16 troops in the open danger close out
HE 2 rounds (or whatever munitions suit you story situation) over (if adjusting fire, the munition isn't specified until you have it bulls-eyed and call fire for effect)
HE 2 rounds out
(fire control computes time on target and warns when impact is a few seconds away)
Splash over
Splash out
If you want to keep it an airstrike, higher command will give the clear to engage, not the guy on the ground. He's nothing but an observer for combat control in this case.
Over and out is fiction.
Over means it's your turn to talk.
Out means we're done
Also, I'm assuming encrypted communication. If not, fire control with say "authenticate (a,b)" the guy calling for fire will check the day's code chart (looks like a multiplication table) and read back what's at the intersection of the two letters FDC called. this goes right after the target description
If you're going to write a lot of this sort of thing, go to EBAY or an Army/Navy store and buy some Field Manuals. They aren't classified (Technically, they are, but at an extremely low level. You're not supposed to just go around handing them out)
You can learn all sorts of stuff about steps military personnel take, how they use the radio for various purposes etc. - then talk to some vets to get a feel for some common "off the books" stuff they sometimes did instead.