A company backed by some big names in high tech emerged from stealth Monday to announce a service designed to let business users know how best to reach colleagues at a given moment, be it via instant messaging, telephone or e-mail.

The new company, Tello Corp., is the brainchild of Jeff Pulver, a founder of Internet calling company Vonage Holdings Corp.

Also on the board are Craig McCaw, who founded the company that later became AT&T Wireless; and John Sculley, the former chief executive of Apple Computer Corp. and PepsiCo Inc.; as well as telecom investment banker Michael Price.

The four men founded the company in 2004, providing the initial capital. While working in secrecy, the San Mateo, Calif., company attracted money from the investment arm of Intel Corp. last year.

Tello's product is a combination of software and an Internet service that extends a feature of instant messaging programs like AOL Instant Messenger, which tell a user if a contact is logged on and available. In tech-speak, this is "presence" information.

When set up to connect to a corporate telephone exchange or Internet calling service, Tello can tell a user if a contact is on the telephone. Likewise, a BlackBerry wireless e-mail device with Tello loaded will tell Tello users if the owner is available.

Tello also collects information from instant messaging programs, including AOL's, Yahoo's, and business-oriented messaging systems.

"Jeff [Pulver] really saw this as taking some of the technologies that were available in the consumer space and making them more usable in a business setting," said Doug Renert, Tello's CEO.

Microsoft Corp. and IBM Corp. have programs that do similar things, Renert said, but these are focused on communications within a company, whereas Tello is designed to connect to people in other companies as well.

"The idea of 'presence' has been out there for a long time, particularly with these instant-messaging applications. The issue there is you often have to run many applications to get a fix on someone," Renert said.

Those who are cautious about how much information they want to show others, like how much they talk on the phone, need not be afraid of Tello, Renert said.

"You can decide who you want on your list and how much information you show them," Renert said.

Tello's program also contains a collaboration feature from software partner Persony Inc., which lets users see and edit documents on each other's screens.

Software with similar combinations of message management and collaboration tools have been on the market for a while.

Convoq Inc. and Groove Networks, now a subsidiary of Microsoft, are two contenders. However, their products generally don't connect to telephones and mobile devices.

A limited version of Tello is available free, with a 30-day trial of the collaboration feature. The fully featured version costs $30 per user per year.

The BlackBerry is currently the only mobile device compatible with the service, but Tello plans versions of its software for so-called smartphones running Windows Mobile or Symbian software.

It also plans to interface with the Skype Internet calling software to show availability.