Now, we need someone to package Asterisk in a form that democratizes telephony to people without Federal Excise Fees (taxed for the privilege of doing local communications), Transit Taxes (paying for mass transit despite the fact you're not using it because you're using the phone) and many other "Taxes" or "Non-governmental Taxes" (things that are called "taxes" but aren't mandated by any governmental organization. (See http://www.cavtel.com/support/Taxes_and_Fees.shtml for all the shenanigans.)
Get rid of "phone numbers" and just give everyone as many 160-bit "numbers" as they want for their phone numbers. Allow people to change these numbers whenever they want. If they experience harassment, make it easy to set up whitelists for conditional forwarding (if the originating call isn't on the whitelist, forward it, tell those on the whitelist what the new number is, etc.). These calls could be forwarded to the "Internet enforcers" that are so keen on outing Internet douchbags. Use DHT's for directory services/yellow pages and set up a gigantic overlay "network" on the Internet (using strong encryption where allowed).
Then you can start destroying the $~500B telecom industry with a "software application." $7B is nothing, go for the big fish. Don't attack hardware (in this case, PBXen), attack systems. Here, we're just going to cut out earmarked taxation and faux earmarks from your phone bills and corporate inefficiency (How much of your phone bill is going to all that marketing to convince people to use something they already know they want/need?) It's far more gratifying.
[/rant-off]