[Nosey]

banden: it has nothing to do with porting a number, gv is just a relay service, so to speak, it's all about call forwarding, someone calls your gv number and it does a call forwarding to your number(s), if you choose the "use your own number" with gv all that is doing is changing who your cell phone forwards unanswered calls to (a cell phone uses 3 call forwarding options, transparent to most users and unchangeable to most)

cell phones use conditional call forwarding for voicemail, (1)forward if no answer, (2)forward if unavailableno service and (3)forward if busy... some phones you can see the number that your call is forwarded to, it's forwarded to a central number with your cell company that see's the call is being forwarded by your cell number and directs the call to your voicemail box

so it's all about call forwarding and knowing how to correctly (if you even can) forward your cell number to gv or if you can't then setting up a gv number and not giving out your cell number to anyone but instead give out your gv number