"I will have called her before you have arrived there."
Translation:Jag kommer att ha ringt henne innan du kommit dit.
har kommit is fine, but kom would mean "came", so it's the wrong tense.
Are innan and före synonyms, I mean can one use them in all the same situations? I tried före here but it wasn't accepted.
"Jag kommer att ha ringt henne innan du är framme" is the closest I can get. The sentence doesn't imply exactly where you are going, but it should be clear from context.