BT is in talks to buy Silicon Valley internet-phone software developer Ribbit as it looks to create a one-number web-based communications platform to take on the likes of Google and Skype in the burgeoning online telecoms market.

Ribbit, founded two years ago and based near Google’s headquarters in Mountain View, claims to be “Silicon Valley’s first phone company”. It has created software that allows programmers to design applications that tie together mobile phones, fixed-line phones and even social networking sites into a single online communications hub.

Reports in the blogosphere said that BT is spending $55m (£28m) on the company. No actual deal is understood to have yet been signed off, and BT refused to comment today.

Bringing together the information stored on the internet with mobile phones and computers, a trend known as unified communications, has been mooted for many years. But the take-up of broadband and the creation of fast mobile phone networks has made it easier to achieve. Last year Google snapped up another Californian company involved in this area, called GrandCentral, for about $50m.

Ribbit’s technology is open to any software developer to use - a model known as open source - so they can build their own applications. London-based Square Circle, for instance, has created a web-based phone application that looks like a chalkboard. American business communications group Salesforce.com, meanwhile, has a Ribbit-based application that lets a company’s sales people keep track of all their calls and contacts through a single web page and costs $25 per user per month.

Ribbit is also testing a consumer platform called Amphibian, which looks like a social networking site with a phone attached. It allows users to transcribe voicemail messages left on their mobile as text on a web page, meaning they can search for keywords in a message. Calls can be patched through from a mobile to a computer; not only will the caller’s number be displayed but Amphibian can pull up their profile and latest postings from sites such as Flickr, LinkedIn and Twitter.

Because the system is open, calls from other web-based telephony services such as GoogleTalk and Skype can also be accessed.

Google, too, is experimenting with open-source mobile communications with its Android mobile phone operating system, due to start appearing in the first generation of handsets towards the end of the year. Application developers are likely to use the platform to create unified messaging services. Apple, meanwhile, is also letting developers create applications for its iPhone device and a Ribbit service has already been created.

Ribbit has raised about $13m from venture capital firms Alsop-Louie Partners, Allegis Capital and KPG Ventures. It was co-founded by serial entrepreneur Ted Griggs who serves as chief executive, former AT&T product development head Crick Waters and two of Griggs’ colleagues from his previous company, telecoms software group Syndeo Corporation: Peter Leong and Ramani Narayan, Ribbit’s head of marketing, meanwhile, used to be head of marketing at another Californian start-up in the web telephony market called Jajah. He previously worked for Apple.