When working online, it’s a simple matter to open a new browser tab and quickly look something up, or to send an instant message to a friend. Ditech Networks, based in Mountain View, CA, hopes to bring the same kind of functionality to phone calls. The company has developed technology that lets users access certain applications in the middle of a mobile phone call.

The divide between the Internet and the phone system has already begun to blur. Voice over Internet Protocol (VoIP) technology allows voice to run alongside other kinds of Internet traffic. Smart phones that offer easier access to the Web have introduced Web applications with voice functionality–for example, Google’s voice-activated search iPhone application or a voice-based note-taking service that works with any cell-phone, offered by Seattle company Jott.

Ditech hopes to let users access many more applications without even having to take the handset away from their ears. “What we’re really doing is … starting to make voice and phone calls truly a digital technology,” says Todd Simpson, CEO of the company. Ditech’s system, called the mStage platform, is a layer of software that a mobile carrier adds to its network. Once mStage is installed, users can access a voice service by saying certain keywords. For example, in the course of a conversation about meeting for dinner, a user might want to search for the nearest pizza place. A keyword, such as the name of the pizza chain, could trigger a menu from which the user could select a search application to return results within the call. The platform can also insert a quick message into a user’s phone call–for instance, briefly breaking in to whisper a meeting notification in the user’s ear.

To demonstrate how other software could connect to the mStage platform, Ditech has created a compatible Facebook application. Assuming mStage is implemented by cell-phone carriers, the app will show when a user is on the phone and let her friends send messages into those calls. Simpson says that this could serve as a way to quickly update a friend about evening plans, without completely interrupting her current call.

One of the big challenges of creating such a system is that it has to scan through a large volume of calls in order to “hear” relevant commands. “The processing on the voice has to occur in real time,” Simpson says. “We want to offer the service to anybody at any time, and so you have to be inside of every conversation in the network.” He says that Ditech built upon existing technology that the company developed to improve the voice quality in mobile calls, which requires a similar level of processing across a network.

Despite processing the content of so many calls, the company stresses that it is careful to safeguard users’ privacy. Hossein Eslambolchi, Ditech’s technical advisor, says, “There is no recording in the whole conversation process at all.” He adds that users will be able to set rules that determine when the mStage platform can access the contents of a call. Beyond that, the system only activates in response to keywords, and then only to invoke the necessary application.

Rebecca Swensen, a research analyst with IDC, says that the communications industry is at a turning point, given the emergence of so many voice-activated Web applications. She points to BT’s acquisition of Internet telephone company Ribbit last year as a sign that carriers are looking toward Web technologies. “The traditional carriers are really starting to understand that they need to do something to catch up,” she says.

Ditech’s mStage platform could well be attractive to phone networks, Swensen adds, since it opens a network to third-party applications, but still provides them with a measure of control over the services being offered and the overall security of the system. However, Swensen notes that it’s equally important to consider whether people are ready to use services like this: “Consumer behavior’s always going to be an obstacle,” she says.

Simpson says that the mStage platform will be ready for carriers to start testing in about three months. The service won’t be available until a carrier decides to incorporate mStage and offer it to its customers, but Ditech hopes to grab the attention of some carriers when it demonstrates the technology next week at the Mobile World Congress in Barcelona.