If you’re hoping to use your fancy G2 to suck up a ton of bandwidth, you’d better be careful because T-Mobile said it will throttle users who go beyond 5 GB a month.

Beginning on October 16, T-Mobile will begin to reduce data speeds when a customer reaches 5GB of usage in a billing cycle, in accordance with T-Mobile terms and conditions. This change should only affect extreme data users (less than 1 percent) and is being made to ensure that all subscribers receive the best Web performance available by limiting the number of extreme data users on our network. The majority of T-Mobile customers should not be affected by this change. The new 5 GB threshold limit, which is equivalent to approximately 125,000 yahoo.com page visits, is enough bandwidth to satisfy most customers’ Web and data needs. If a customer happens to reach the 5GB limit, they will receive a free text message informing them their data speed will be reduced. Customers will continue to have Web browsing capabilities but at slower speeds, which will be determined by their device type. Once their new billing cycle begins, data speeds will no longer be restricted.

Customers can track their data usage through My T-Mobile, MyAccount, or the SIVR.

That does sound pretty reasonable actually, as I’m a mobile fanatic but I’ve never even come close to hitting 5 GB of data in a month. But you do have to wonder if those caps will raise as technology gets better.

That G2 can use HSPA+ and we’re still waiting for an update which will allow it to act as a mobile hotspot. When you consider that the T-Mobile HSPA+ 3G network can get up to 21 Mbps, it may soon be really easy to suck up bandwidth.

Any of you readers come close to that 5 GB cap? Let us know in the comments.

[Via Boy Genius Report, photo]