Today AT&T announced a new unlimited voice plan for wireless customers. Priced at $100 per month, the new plan will be available February 22nd and can be used by iPhone customers. However, iPhone customers will still be required to have AT&T's $20 data plan in conjunction with the unlimited voice package.
We've confirmed with AT&T that no contract extension is required to use the new plan.
Upgrading to the unlimited plan, according to AT&T, requires "visiting company-owned retail stores and kiosks, at www.att.com, or at one of the thousands of authorized AT&T retail locations."
As confirmed in-house, however, you can also call AT&T's customer service line (800-331-0500) right now and ask to be called on February 22nd for an immediate upgrade.
Meanwhile, Phonemag.com reports that the option "will show up in iTunes shortly." We assume this refers to customers establishing new lines of service with iPhones, though an iTunes-based upgrade option would certainly be welcome.