Not to be outdone by Verizon’s announcement yesterday, AT&T and T-Mobile also announced new unlimited voice plans for just $99.99 a month; AT&T’s plan is set to start Feb 22, while T-Mobile’s plan goes live tomorrow.

Yesterday, Verizon Wireless led the pack by announcing a $99.99 anytime calling plan.

AT&T says its new plan will be available to new and existing customers, and will be compatible with any current wireless data plan. Existing customers can switch to the new plan without having to extend their contracts. T-Mobile’s all-you-can-talk plan also includes unlimited text messaging.

“We are pleased to offer our customers these great new plans that deliver value and simplified pricing,” said Ralph de la Vega, president and CEO of AT&T’s wireless division, in a statement. “This is a highly competitive market and we’re committed to moving fast to meet customer needs.”

“This offering empowers people to communicate as much as they like on their own terms – whether it’s voice, text messaging, picture messaging or IM,” said T-Mobile’s Vice President of Marketing Jeff Hopper, in a statement.

With Verizon, AT&T and T-Mobile offering the same unlimited pricing plans, the question now is what Sprint might bring to the table.

Sprint has been steadily losing subscribers and has been looking for ways to stop the bleeding; some analysts speculated that it might try to beat Verizon and AT&T’s unlimited pricing models. Sprint recently launched a $120 per month unlimited plan, which includes voice calls, texting, mobile Web and mobile e-mail in select markets. And though the carrier has said the test markets are going well, it is unclear what effect the new unlimited rates will have on the wider market. Analysts estimate that the new plans only pertain to the top 10% to 15% of wireless users.