Most of us have figured out some basic rules for reaching other people: If it's urgent or if you've never met before, you make a phone call to their landline. If you're sending detailed information, you send e-mail, perhaps with an attachment. If you're friends and just touching base, you might send an instant message or call their cell phone.This approach assumes three things: first, that you've got all the relevant contact information; second, that their preferences on how to be contacted correspond with your preferences for contacting them; and third, that nothing ever changes (people don't decide to temporarily prefer being called instead of e-mailed, for instance).Most of the time at least one of these assumptions is wrong - and you end up playing voice mail tag, or seeing your e-mail messages getting sucked into a giant black hole.What if it were possible to avoid all these rules of thumb by querying a global database to find out not only how to reach a person but where they are currently and how they'd prefer to be approached? For example: "Johna Johnson is currently at her desktop accepting e-mail and instant messages but not telephone calls."Or, "Johna Johnson is away from her landline and desktop but reachable by cell phone or e-mail."And imagine if that information were followed by the options: "Click here to contact Johna by her preferred options now . . . or click here to leave a message for her to contact you later. "The database might provide different responses based on the identity of the inquirer. For example, "If you're a telemarketer, Johna is never, ever available. But if you're a client, the phone number at the emergency room where she's being treated is 555-1212."That, in a nutshell, is the concept of\u00a0presence. Technically speaking, a presence server is a directory capable of storing the information described above - in real time. If you move out of cell phone range or turn off your phone, for example, the presence server no longer lists your cell phone as a way to reach you immediately.A handful of vendors are beginning to wrap their minds around the concept of presence and how to implement it in the real world. An even smaller handful of IT executives are exploring how presence can make them, their staffs and their organizations measurably more productive.Presence represents one of those once-in-a-decade paradigm shifts (like telephony and e-mail) that radically changes the way people interact and that it will have a substantial effect on vendors, users and next-generation communications services.The weird thing is not one phone company executive I've spoken with has the faintest clue what I'm talking about. You'd think they'd pay some attention, if for no other reason than competitive concerns. Phone companies have spent trillions of dollars over decades building an infrastructure for connecting phones to other phones. But the presence paradigm is all about connecting people to people - phones might not even be involved. Don't you think it's time for the phone companies to wake up and pay attention to presence?