AT&T today announced new voice plans for unlimited U.S. calling on all devices with no domestic roaming or long distance charges, available for $99.99 a month.

Existing customers can choose unlimited calling without extending their contract. New customers have the option of a month-to-month, 12 or 24 month contract.

"We are pleased to offer our customers these great new plans that deliver value and simplified pricing," said Ralph de la Vega, president & CEO, AT&T Mobility. "This is a highly competitive market and we're committed to moving fast to meet customer needs."

Verizon Wireless set off a stampede to unlimited voice plans among U.S. mobile operators on Tuesday. AT&T joins Verizon Wireless and T-Mobile to recently announce unlimited plans. Sprint hasn't offered any indication of following suit.