In May, I blogged about “Silicon Valley’s first phone company” which was creating a new market opportunity for Software-as-a-Service (Saas) in the voice communications sector.

Today, BT announced its intention to acquire that “Telco 2.0” platform company, Ribbit, for $105 million in cash. Not bad for a company which just closed a “small” B round of funding, according to the company executives I chatted with this afternoon.

This acquisition clearly demonstrates how far SaaS has come.

SaaS is no longer viewed as just a cheaper and easier alternative to traditional, on-premise applications. Instead, SaaS is becoming recognized as a way to fundamentally transform businesses processes and various industries, such as telecommunications.

My roots are in the telecom industry. I helped to launch IDC’s communications industry research program in 1983 at the time of the original AT&T divestiture. I also enjoyed my most satisfying and successful years in the ‘real-world’ working at International Network Services (INS) in the mid- and late-1990s, which helped incumbent and insurgent telecom companies deploy router-based networks to support a new generation of business applications.

I’ve always viewed BT as among the most visionary of the major telecom companies. It acquired INS in February 2007. It has built a strong working relationship with Microsoft as a hosting company and purveyor of their Software-Plus-Services.

At the time of BT’s acquisition of INS, I wrote in the Web Hosting Industry Review (WHIR) that SaaS could enable telecom companies to escape the commodity business of traditional transport services and create new, application layer opportunities.

BT boldly stated in today’s announcement that the Ribbit “acquisition will accelerate BT”s strategy to transform itself into a next- generation, platform-based, software-driven services company.”

BT not only gets an innovative company, it also gains inroads into the Salesforce.com world of AppExchange partners and its Force.com development platform.

In order to minimize the risk of ‘killing the golden goose’, BT plans to operate Ribbit as a separate subsidiary retaining its name and management team so they can continue to pursue the promise of a new generation of voice-as-a-service solutions.