You are headin away from me at any speed. I send a signal that reaches you instantaneously in my frame. You reply with a signal that reaches me instantaneously in your frame, which arrives before I sent my signal.Can you give an example of faster than light signaling that will create reference frame in which the signal arrived before it was sent ?
You can do it with non-instantaneous communication too, but the circumstances where things go acausal are a bit more restrictive and I'd need to do some maths.
You could Google for "tachyonic anti-telephone".