Virgin Mobile is a newcomer to unlimited calling plans

A bit late to the party but arriving nonetheless, Virgin Unlimited today introduced its unlimited calling plan for its customers.

The new "Totally Unlimited" calling plan will be available for $79.99 per month with no roaming and will be available on July 1. For an additional $10 per month, customers will receive unlimited text messaging, picture messaging, e-mail, and instant messaging.

Subscribers may escape activation fees and an annual contract, which could make Totally Unlimited cheaper than similar plans from Verizon Wireless, T-Mobile, Sprint Nextel, and AT&T. Verizon kicked off the party in February after announcing unlimited voice calling for $99 per month. T-Mobile and AT&T followed suit by offering $99 per month for unlimited voice and texting. Sprint Nextel's $99 per month service features unlimited voice, text messaging, e-mail, video, and Internet.

Meanwhile, Virgin Mobile has struggled to keep users and attract users to its pre-paid service. Its 5.1 million customer base makes Virgin the biggest mobile virtual network operator (MVNO), a term describing a company that relies on other networks to provide its service. In this case, Virgin Mobile relies on Sprint Nextel's infrastructure.

Furthermore, Virgin Mobile's average revenue per user was already $19.93 per month -- half the amount other carriers make.

There were talks about a merger between Virgin Mobile and Helio, but nothing official has been announced as of yet.

A similar prepaid service, Page Plus Cellular, charges $2.49 per day (about $75 per month) for unlimited voice, though roaming is not included.

Virgin Mobile offers a small selection of phones to its users, with many popular manufacturers and models not available. Today, its top phone is the Slash, which features a built-in camera, phone, Bluetooth, music storage, and ringtones for a $79.99 charge.