Calypso Wireless (fka CLYW)

[p2k12]

dirt, read the jan 2010 zdnet article in your link a little closer

Subscriptions were between $10 to $15 per month for unlimited calling for phones plugged into a broadband-connected adapter.

in jan 2010, zdnet made the same mistake several other news outlets made: they mistook tm's landline replacement voip broadband adapter based vonage-like @home product for tm's similarly named wifi enabled gsm smart phone based hotspot@home service. not sure anyone has mistaken tm's marketing acumen for apple's.

check out this jan 2010 retraction from engadget:
http://www.engadget.com/2010/01/12/t-mobile-killing-hotspot-home-service-softly/

Update: As a number of you pointed out it seems we've got things a bit wrong here courtesy of some conflicting reports. The HotSpot@Home service will live on, but the @Home service, which provided VOIP access through landline phones, is the one being put out to pasture here.

here's a feb 2011 link with some stats, a diagram, and links to other articles:
http://www.fiercewireless.com/story/t-mobile-usa-offloads-5m-wi-fi-callers/2011-02-16

here's a june 2012 article that will likely generate some reactions:
http://www.kineto.com/wi-ficellular-handover-the-state-of-the-market/

it appears tm launched hotspot@home on a limited number of wifi enabled smartphones in 2007 and supported handover in at least the wifi to gsm direction. in late 2010, tm launched a wi-fi calling service on new android smartphones that appears to not support handover in either direction. it appears that as legacy hotspot@home subscribers migrate to newer smartphones the hotspot@home service will eventually fade away.