Welcome to the forum @Apriltld. When you have a chance, head over to the Newbie Section (<click this) and say "Hi".
Tell us a little about yourself and your ride.
That way we can welcome you all proper like.
Phone calls won't work unless you have the U-connect module. Mine did not have it, so I had to add it.
Mech Error is just that. Some kind of mechanical problem internal to the radio.