If you have a 2GB data plan with AT&T, you're about to save some money on your wireless bill. Starting tomorrow, March 9th, the company is dropping the price of its 2GB Mobile Share Value plan by $15, from $55 to $40 per month.

Like all of the carrier's shared data plans, you'll need to pay an extra monthly fee for each device that accesses that data pool. That cost is remaining the same at $40 per month for each on-contract smartphone and $25 per month for smartphones purchased at full price or through the carrier's Next installment plans. All Mobile Share Value plans have unlimited talk and text, as well as free texts from the United States to international numbers. The carrier is also offering 50GB of cloud storage on its own service with the plans.

If you already have a 2GB plan on AT&T, you might save $30 per month

A $15-per-month discount on AT&T's popular 2GB plan is good news, but even better is the carrier's offer to its current customers. The company will let any existing customers who start using the new 2GB plan switch over to the lower $25-per-month smartphone device fee. That means that even if you are in the middle of a service contract for the last smartphone you bought with AT&T, you can drop from paying $40 per smartphone down to $25. It's worth noting, however, that the price will jump back up to $40 if you purchase your next phone on contact. Nevertheless, for AT&T users with 2GB individual plans, this change combined with the price cut announced today means that your bill could drop by a total of $30 per month starting tomorrow. Unfortunately, you will need to change your plan online, over the phone, or in a store to get the new pricing.

Along with the revised 2GB price, AT&T's old 1GB plan — which used to cost $45 per month — is being canceled. Inexplicably, current customers on that plan won't automatically be switched over to the new 2GB bucket, which is $5 less per month and comes with twice the data. You'll need manually switch.

With the price cut to the 2GB Mobile Share Value plan, AT&T is getting its pricing more in line with the plans offered by T-Mobile and Sprint. Like many recent changes to rate plans, this move likely comes as a direct response to the prices set by those two smaller carriers. Indeed, AT&T has struggled to keep up with T-Mobile's subscriber growth since it began its "Uncarrier" transformation last year, which has spurred a number of changes through the wireless industry. It's great to see lower prices get passed along to customers, though Americans still pay far more for wireless service than people in other countries.

Update: Now that the plans are live, a bit more information is available. AT&T will let any customers who signed a contract on March 8th, 2014 or earlier get the $25-per-phone pricing if you switch to a qualifying Mobile Share Value plan. That's a $15 per month savings over the typical rate for on contract phones. The 2GB, 4GB, and 6GB data tiers are valid for the promotional rate. If you upgrade to a new phone on contract in the future, the rate will go back to $40 per phone.

A similar promotion last month gave existing customers with 10GB or larger Mobile Share Value plans the opportunity to pay $15 per line instead of $40. You can still take advantage of that pricing so long as you signed your current contract on or before February 1st, 2014.