NEST just announced in CES that it will soon work with Ooma VOIP.
https://nest.com/blog/2015/01/05/what-works-with-nest-at-CES/e.g. "Ooma VOIP home phone service works with Nest to learn when you come and go. So if something unexpected happens – like your kid doesn't come home from school on time – it can send an alert to your phone."
Not sure how it is implemented, and if we can get something similar going with OBi devices? Any
IFTTT possibility?