I recently received a promotional email from Amazon offering the Linksys Tmobile @ Home HiPort for just $15.99. This was the internet router device that has a UMA interface on-board. Add a T-Mobile SIM card and you have cellular trunk line for home use with a traditional wired telephone.
The fact that these devices remain available is a curiosity. T-Mobile still supports UMA calling. That makes me wonder if they could be used in some novel way around the house. I have too many unfinished projects already, but these do seem interesting.