A schedule that has surfaced today hints that T-Mobile is set to join AT&T and Verizon (pictured) with its own Visual Voicemail service. The feature found by TmoNews isn't attached to a particular device but, as with earlier implementations, would send audio file versions of messages directly to a subscriber's phone instead of asking them to call a typical voicemail box. If true, the system would be launched on July 16th, just ahead of a pair of Samsung phones known as the t469 Smiley and t549 XO.

It's uncertain at this point whether T-Mobile's voicemail would emulate Verizon's approach, which is mostly limited to an app for traditional phones, or would support smartphones. The T-Mobile G1 already supports a similar feature but only through third-party apps but has no official solution of its own.

Apple is so far the only handset maker to include Visual Voicemail as a standard feature on its devices by building it into the iPhone's firmware; the Verizon solution currently requires an additional subscription fee and a separate download for those phones that aren't preloaded with the software, which only includes a subset of its entire device roster.