Sprint used to have very bad network. Now, AT&T is worse. Verizon and Sprint are the top good guys. What is even better? Sprint can use Verizon's data/voice network when its own signal is very poor~~
There are two outstanding posts on XDA forum which cover everything you need to let a Sprint HTC EVO 4G phone running purely on Verizon network! Very easy to do, and I did it within 30 minutes.
Here are the two posts you want to follow very carefully.
Below are screen captures of the swapping process I did.
My anti-virus program recognizes CDMA Workshop as a hacking tool and deletes it automatically. Thus, I have to disable it ...
I actually didn't install "HTC Diag Drivers". After dialing ##3424# (the display on the phone shown above) and connecting the phone to my computer, all hardware were recognized! I installed HTC Sync before, and this PdaNet PC client, not sure which replaces the requirement of Diag Drivers.
Mine was connected to COM5, not the COM6 said in the post.
Under "Security" tab, click "Read" and I saw 6 digital MSL code displayed in red marked area. To test it is the correct one, dial ##3282# and enter the Edit Mode. The phone asked me a password. I entered the MSL code. Bingooooo!
Later, I went to a zone where obsolutely no AT&T signal. I notice that Verizon network has weak signal and I can make/receive calls. If I am using Sprint, it switches to the Roaming Mode! Since Sprint has better 3G speed, and switches to Verizon network smoothly, I am staying on the Sprint network!
How to switch back to Sprint? Update PRL in System Update.
To switch to Verizon again? Force the Alltel PRL.