I still have the same home number. Do I need to start over completely by porting by number to Verizon and then to GV? And is there any reason that the Obi110 would need to be upgraded?
Yes, you could take that same path again. You'd need to first port the Time Warner Cable land line number to a prepaid mobile carrier. I don't know why you used Verizon last time, unless you have the ability to port into them without starting a new 2-year agreement. AT&T GoPhone or T-Mobile prepaid are the two most reliable choices.