Despite what the "unlimited" plan might make you think, Sprint is exercising their right to throttle back on users they've deemed as using too much data. Heavy use contract customers on Sprint, as well as prepaid customers on Sprint-based MVNOs Boost Mobile and Virgin Mobile USA, have been hit with warnings that starting next month Sprint will be engaging in "prioritization management" in congested areas.
FierceWireless has an example of the message being sent to customers:
"Beginning 6/1/14, to provide more customers with a high quality data experience during heavy usage times, Virgin Mobile USA may manage prioritization of access to network resources in congested areas for customers within the top 5 percent of data users."
Sprint has for the past several years been beating the drum of their unlimited data plans, touting their status as truly unlimited in the face of tiered plans from AT&T and Verizon, as well as an 'unlimited' data plan on T-Mobile that throttles user speed back if they blow past a soft cap on the service.
The prioritization management that Sprint will be engaging in will be throttling, but they've promised that it will only be in congested areas during congested times. If the Sprint customer that's in that top 5% either leaves the congested area or the congestion eases, their "speeds will return to normal."
As for where that 5% threshold lands, that's hard to say, though Sprint says that a user who uses over 5GB in a month is likely to be in that zone. Again, crossing into the top 5% doesn't mean you're automatically throttled — it's only during peak traffic in high traffic areas, and the prioritization scheme isn't applied to the account until the following month.
Now that Sprint's unlimited plan now has an asterisk on it, does that change your perception of the carrier?