So I recently got a boost moto g, specifically for the purpose of unlocking it and installing custom roms, First I had CM11, ran great but I needed more, then I flashed SlimKat, that was even better after I flashed pink kernel in but, I derped it some how and went back to stock 4.4.2, now when ever I flash a new ROM, it has this dumb activation that dials *22899 and then tells me "we're sorry, we could not complete your activation at this time, please try again later" then kicks me to the beginning and I all get is the option to try and activate again, it even does it on CM11 now. what did do? I followed all instructions to the tee on the rom websites. I just downgraded to stock 4.3, then manually updated to 4.4.2 and now its giving me a "cellular activation bug" update, hopefully this fixes my problem. I'll post again if it does not, Thanks for any insight.
EDIT: The "Cellular activation bug fix" you can receive via manual updates on the stock 4.4.2 rom fixed my issue, If you find your self with this issue, fear not! just flash lowest stock android for you phone and let it update by checking for them via the system update in the system settings. ^.^ (i feel this will be useful to anyone who instantly unlocks the BL and flashes a custom rom before even starting stock like I did)
edit edit: I only worked for one installation, when I tried switching again, it broke it again and got caught in activation again.