In its press release, the company claims to be the first to offer “voice addressing” for text messages. The company claims high levels of accuracy because it is the only application to be “fully integrated with the Android SMS client and uses Smartword, Promptu’s editing tool that lets users see and select from likely word alternatives.” The application debuts today (April 26) for the Motorola Droid with features taht include: voice addressing, “full integration with the phone’s messaging service (including message exchanges threaded by recipient), thumbnail images displayed for contacts and “one-touch navigation to all recent incoming and outgoing messages.

As reported here, Promptu’s revenue model will test the value that users attach to transcription services. If it remains true to form it market bundles of “voice credits” in increments of 50 for $1.99; 150 for $3.99 or 250 for $4.99, as it does for iPhone users. This is in contrast to its closest functional rivals Vlingo (which has charged for a $17.99 for its application on the Blackberry) and Nuance Dragon Dictate, which has not yet announced a revenue model. Vlingo, by the way, has a “beta” of its application for the Android, which has been available since mid-March.

Along with Google, Microsoft and (to some extent) AT&T, these are the initiatives that are shaping the way that spoken words will be integrated into the mobile messaging flow.

While Promptu is similar in function to Dragon Dictation for the iPhone, there are some true differences. For one thing, the application prompts subscribers to “train” the system by reading several individual paragraphs of text, in a process that takes about five minutes. Another difference is that users originate their text messages without leaving the Promptu application. That’s because the developers have figured out a way to use SMTP (Simple Mail Transport Protocol) to send the message as SMS text. The only disadvantage is that the recipient sees a fictitious number (like 001001100) as the return address. Nonetheless, responses to a Promptu originated message are displayed in a series of text balloons that resemble the threaded text messages in the iPhone SMS application.

As another differentiator, Promptu plays back the audio message it captured so that users have something to listen to while the service performs its transcription. Results are displayed on the phone’s screen for review. Corrections can be made and punctuation added by using the keyboard or by selecting the proper word from a “rolling barrel” of most likely matches. Adding the barrel selection to this ‘triage stage’ of message origination is a nice touch as well.

The rapid-fire introduction of speech-enabled mobile apps shows that the technology is coming of age. Now we are ready to learn if wireless subscribers are willing to pay for these services. Promptu is in a better position than analogous service providers to gauge whether a sufficient number of iPhone owners are ready to buy into speech-enabled messaging because it has attached a price (other than “free”) both to the core application and to the bundles of “Voice Credits”. The only other service that I’ve been using that makes use of the iTune store’s ability to support “top ups” or “refresh” of service credits is “kgb Answers” which sells “knowledge” on the iTunes store in packages of 2, 6 and 10 for $1.99, $4.99 and $7.99 respectively. That makes 2010 the year when we begin to learn the perceived value (in dollars or other local currency) for various mobile speech offerings.

That said, we were surprised and a little gratified that Promptu has enough confidence in the impending launch of its ShoutOUT app on the iPhone to post this screenshot on Flickr.

Like Second Life, a screenshot is its own flavor of reality. Still, we have seen real-life demos of a Promptu-based SMS app that supports addressing, dictating and sending SMS messages through an iPhone. It is not totally hands-free and users are well-advised to review and edit dictated text before transmitting, but the promise of mobile speech-to-text messaging moves ever-closer.