That is precisely why I mentioned modern, in particular would be interesting to know if given a good angle they can resolve phone number being entered on a cell phone with physical keyboard (nokia 3390 for example).
Edit: Sorry, understood your comment now. The real problem isn't resolution, it's "getting a good angle". Unless your target and the satellite's orbit are magically aligned at a precise moment, you're going to have an extremely hard time getting a satellite into position in a reasonable time (the best commercial satellites can do is around 6 hours).