Since I've been getting a new phone I've spent a good deal of time lately thinking about the telephone industry. I have several problems with it but I suppose the largest is that I don't want voice service. I really just want to be paying for data. I'm happy to pay for Data at home and Data on the go. But I think it should all just be data. This sentiment is shared by a number of my friends. While you can get data-only plans for smartphones it is not clear to me that they are truly unlimited as some are advertised. I was looking into what would be required to maintain a "phone number" if you did have an unlimited data plan with good coverage.
It seems you would need to use Local Number Portability to transfer your phone number to a virtual number provider which would then route all calls to that number to an SIP address. Then as long as you had an SIP provider that had some way to handle outbound calls to phone numbers you could get by with 3G just fine. I can't tell if Google Voice might wind up resembling such a service but here's hoping, even if that would give Google an undue amount of power in my life. Better them than ATT. There's an SIP app for Android besides the Google Voice app called SIPdroid that looks pretty good and a list of SIP service providers here. The GV Android app presently still routes calls through the PSTN. At least SIPdroid lets you route calls through 3G or Wi-Fi but routing VoIP through 3G likely violates the TOS for most mobile carriers. Oh, well.
Of course, there's an Android app for Google Voice already and it's rumored that number portability is coming to GV soon. We'll see. In addition to that, there are some other good things happening. Verizon is pushing FiOS and a group at nochokepoints.org is fighting for more competitive access to so-called "special access" lines. Finally, someone is trying to communicate how we think to the telecoms which can only do good.