An application that sits on the BlackBerry notifies a user when the first participant joins the conference call, and promises in-call security and visibility in real-time display.

In other words, the conference call participants can see who’s on the call, add participants from their BlackBerry address book, and drop or hold or mute participants. Invitations can also be integrated with Outlook and other email applications.

Users can dial into the conference call from any phone, then take control of that call from their BlackBerry. Ring2 users receive a dial-in calling card, as well as the BlackBerry application overlay, which is ideally implemented over the air through a BlackBerry enterprise service. It also can be downloaded online.

Ring2 co-CEO Steve Flavell said the company would announce a similar application for devices running Windows Mobile OS in the second half of the year. The company also is looking at some Symbian devices, and also is considering Palm OS-run handhelds, he said.

Ring2 also is looking to potentially partner with mobile operators to embed the application on devices, at some future point, Flavell said. Currently, the company is in early-stage discussions with mobile operators to do this, he added.

Unlike WebEx Communications and others, Ring2 is focused solely on voice conference calls, rather than online collaboration with voice, data and video. Co-CEO Michael Hughes said Ring2’s chief rival in the US is InterCall Inc.

The Ring2 BlackBerry service costs as much as 15 cents per minute, with a one-off $15 set-up fee per user. This is roughly at market price, Flavell said.

The sweet spot for the company would be enterprises with 1,000 or more BlackBerry users. The price for the service goes down to between 10 cents and 12 cents per minute for contracts of this size, he said.

Alcatel’s VoIP SIP-based collaboration media mixing technology provides the backend infrastructure of the service. The actual application is based on Ring2’s proprietary protocol.

The company launched in February 2003, and has garnered an undisclosed first round of venture capital, as well as funding from about 40 separate angel investors. Flavell said it would seek more funding this year, which it will spend across the board to support anticipated growth.

Ring2 launched its first product in mid-2005, a PC-based click-to-call application for SMEs.

But its mobile conference calling product is expected to be its cash cow

London-based Ring2, which has an office in San Francisco, would more than double its current 20 employee headcount by 2007. Roughly half of its existing workers are in the UK, with the remainder in the US.

The Ring2 service is available globally, but the company currently provides support in the UK and US only.