Perhaps I don't understand how you would make it more open if you were the FCC. (See P.S.)

1) The FCC has mandated number portability which was the biggest barrier to switching carriers.

2) I can buy an unlocked phone from a third party (like Nokia) and use it on any carrier which supports the radio my phone has.

3) I can choose to sign a contract or pay as I go for services.

I can think of ways to make it benefit me more (like require all carriers to convert to CDMA because I have an EV-DO chip in my UMPC), but I can't think of much that the government should be doing.

P.S. One "open" issue did occur to me and that is market entry. It is true that there are a limited number of carriers who have purchased segments of the spectrum from the government. This was an open process. At the time I worked for MCI and we lost the bid for the first nationwide spectrum allocations to Sprint and AT&T. But once the spectrum was all allocated, the market became an oligarchy. I'm not sure what you could do to change this although I will point out that competition between companies in the oligarchy still exists and does elicit change (e.g. Verizon's recent cuts in the unlimited voice pricing to compete with T-Mobile).