gdgt

There's no way. It awfully anticonsumer. I hat wish the government would step in to change it. If I had my way I'd start by banning carriers from selling phones. More realistically I think that all companies should be required to have cellphones that are all LTE and able to be unlocked to run on any other carrier.

And Unlocked t-mobile phone should work on At&t, The Problem is 3g, because t-mobile uses different bands for 3g than they do 2g, and At&t uses the same bands for their 3g as their 2g., Phone should still function properly though, just don't expect 3g speeds. Although many t-mobile phones will also use 3g on the at&t bands as well, just depends on the phone. didn't look your phone up, so can't say for certain.

I also don't see it as being anti-consumer. The carriers have to pay for their own networks, so they go with what they believe is best. Also when you sign a contract, you get the phone for way less than what you would normally pay for that phone. While I would like to see all companies go LTE and use all the same bands, if it were mandated that they do so, our government would have to pay the cellphone companies to all switch over to their networks, which would be a huge undertaking, and very expensive. This would also put government oversight over all cellphone carriers, and would make the technology basically be locked down. It would end up becoming just like the big telecom industry of the 50s through the 80s, where government paid to install the base, and they directly had say over the companies involved. It slows technology way down, and puts the companies into oversight committees, for no good reason.

The basic truth is I prefer the companies the way they are now, although one major merger going through right now, that I do believe the government should block is At&t buying T-mobile, I do not believe this is good for the Cell Phone industry,, puts two companies basically holding a monopoly of the market.

You also have the option of going prepaid, you can unlock a phone and use it on many different pre-paid services, now if a certain prepaid service doesn't support a band, you'd still be in the same boat.

Short answer: YES

Your question: Is there any Android-based (or any) phone in existence that supports all the major US carriers?

Answer: I was not able to find an Android phone for WORLDWIDE use. I therefore purchased a competitively priced unlocked C6-01 Nokia phone ($250) running the Symbian Anna (or Belle) operation system. (Symbian is supported until 2016).
This phone has all the GSM (voice) frequencies and all the UMTS (data) frequencies used WORLDWIDE.
It also has GPS and you can download maps of 180 countries (without using a dataplan). This is a must if you are in a location with no data coverage - also saves money and time if you have a data plan as the maps are already on the phone. Live traffic conditions are also shown (if you have data coverage).
Public transportation and walking trails are shown as well (without data coverage)
The screen is a super bright amoLED with Gorilla glass, the phone is compact and perfect for travel. The display always show the time with very big numbers (almost a hotel clock).

A true WORLD PHONE should have these frequencies:
GSM 850 / 900 / 1800 / 1900
UMTS 850 / 900 / 1700 / 1900 / 2100

I love this phone!!!
Also you can EFFECTIVELY turn off the data connection and wifi. Yet you can set it to ask before it connects (if an application requests data).