AT&T started throttling its heaviest unlimited data users last
October, but is only now explaining who gets throttled and when.
AT&T has posted an info page
with details on its throttling policy. “Throttling” a data plan is when
a carrier promises unlimited (or a large amount) of data, but starts
slowing users down when they approach a soft limit–data is still
technically “unlimited,” but it’s no longer happening at premium speeds.
Throttling continues until the next billing cycle.
According to AT&T’s info page, throttling occurs after 3GB of
data for users who have 3G and 4G HSPA networks, and after 5GB of data
for users who have 4G LTE phones. Note that this only occurs for users
who have been grandfathered in on unlimited plans–it does not occur for
users who have tiered plans.
