This article gets into SIP, the technical standards that enable mobile presence — a key smartmob technology.

(Via Mobitopia)

A traveling worker hears a unique ringtone on his cell phone, checks the screen and finds a presence notification that a colleague is awaiting a plane in the same airport.

A ’soccer parents’ presence channel’ on a dad‚Äö√Ñ√¥s SIP softphone shows all the team‚Äö√Ñ√¥s parents are available to share a group voice or IM session right now.

A teenager who just wrecked his mom’s car checks the family presence channel on his mobile phone to find out his mother’s current mood.

These examples only hint at how presence technologies will enable a large class of services not achievable on existing mobile networks.