I believe that in a few years Google-Voice (GV) will be significantly larger than it is now, and that will be due to growth in the Desktop/Mobile user segment not standard-phone users. The advantage will all boil down to the fact that GV gave users a free US phone number to start with.

Here’s how things will evolve:

• iPhone OS4 comes out, VOIP apps can run in the background
• People start using Skype all the time in the background and whenever they have WiFi its great
• GV will come out with an iPhone app that does their VOIP calls over WiFi as well (that’s legit and Apple will approve it)
• Guess what, GV gives you a free incoming number so you can now make and receive calls, most of the time (when you’re on WiFi and heck maybe also on 3G)
• This will all be replicated (if not executed earlier) on Android devices which will find GV to be the default VOIP app, and oh yeah did I mention you get a free US number?

This battle will be over the segment of users who are around WiFi coverage enough of the time and have smartphones that will allow them to use WiFi for making/receiving calls when its available. GV’s architecture lends itself beautifully to this as it gracefully degrades from direct VOIP calls to standard ‘to your phone number’ calls. Skype has similar functionality though its really not implemented so well and Skype’s focus has been solely on the VOIP-calls segment while GV started from standard calls and will now expand with Desktop/Mobile VOIP apps.

GV’s current issues with call-delays (caused by the fact that all calls are tunneled through Google servers so that Google can provide conferencing/recording functionality) will go away. All these features will be implemented on the user’s Desktop/Mobile-device and so call quality will go up and lag will go down to nothing.

Its going to interesting and fun, can’t wait to get GV background app on my iPhone.