Can anyone here share their experiences with using the AT&T international data add-ons? As in, when is a good time to add it (how far in advance) and how long should you keep the plan in place to ensure it catches all the international data?
I add the plan at the beginning of my billing period when I know I am going to be overseas and I don't delete it until the first day of the next billing period after I return.
AT&T basically pro-rates whatever you add on. So if you add a 20 MB plan 10 days before the end of your billing cycle, you get 10/30 * 20 MB or about 6.67 MB of usage. They also charge you only 1/3 of the total cost. I prefer not to mess with it and just keep the plan for the whole month. That way I know for sure what I am allowed to use.