YouMail, a relatively new and free tweak within Cydia, allows those with unlocked iPhones (or even just carriers that don’t support visual voicemail) to experience this missing feature. YouMail essentially replaces the built-in visual voicemail within iOS, giving jailbroken iPhone users the same native experience they would get with the official carrier-supported visual voicemail.

Word from MacNN has it that Apple and AT&T may together add support to the iPhone for overage alerts and new Voicemail settings. These feature may find their way on to an iPhone near you as soon as iPhone OS 3.1, which we are expecting in the not too distant future.