For sero:
Go to sprint.com/sero
In the box which requires a referral email, type
savings@sprintemi.com
That email address works about 95% of the time. If it doesn't, google Sprint Press release, and use the Sprint corporate email address at the top of any of the resulting pdf's. Its as simple as that. Its an amazing deal, unbeatable in wireless imho. Its 500 minutes+unlimited data for $30, and sometimes they even throw in free texting.