After adding my BYO iPhones to my account, I've found that one isn't using enough data to justify paying for unlimited, but it very well may in the future. If I were to switch from unlimited to by-the-gig before the end of the current period and then discover the next month this phone needs to be back on unlimited, can I then switch back to unlimited?
I only ask because I learned the hard way when I switched another phone from gig to unlimited that I had to remain on unlimited for the month I switched it as well as the following month, but I am unsure if it is the same going from unlimited to gig and Xfinity doesn't document these details very well, if at all.
My guess is yes because unlimited is prepay - you are charged immediately upon switching and then at the beginning of the next cycle - whereas by-the-gig is postpay. It is advantageous to XM to have you on the unlimited plan because they can collect money first even though you could end up paying more with by-the-gig if your usage exceeds 4 GB.
From what they advertise on the site, you can switch to Unlimited whenever you need it. It sounds like you should be able to switch from Unlimited to By the Gig without paying for another month if you do it by the end of your billing cycle. I assume the end means the last day of the cycle. It doesn't sound right that they'd charge Unlimited for a second month, unless you didn't make the switch until the first day of the next cycle or after.
Guess I could have looked and answered my own question. Seems like there's always a got'cha with Xfinity. Guess since I'm on unlimited this billing month (ends 3/12), I also need to be on unlimited for the next month and then can't change it until 3/13 for the following month. Would seem to me that I should be able to switch it now for the month that begins 3/13.