Personally I don't think the range should be more than x10 per +2 levels, and clearly not through the planet, since you traditionally can't even teleport more than a mile in the Underdark; clearly heavy masses and electromagicomagnetic fields prevent teleportation, Star Trek style.
Going "over the hump," and if my calculations are right, 130,000 mi should be enough to cover half the mean circumference of any terrestrial planet and all gas giants except Jupiter (~41,400 mi in radius).