I just found this way to haxor a samsung A670 to change the volume, remove the annoying verizon banner, and mess with the service LED.
WARNING: Doing this wrong can and will brick your phone
Press "47*68#13580" and you will see a screen pop up saying "test cdma". press "02" to restart the phone and exit this mode at any time. there are many 2 digit numbers that do interesting things in this mode. "28" says "led color_7" and you can press diferent numbers to see the different colors the service led can do. "99" lets you mess with the volume levels, and i think there might be a way to lower or remove the camera shutter sound, but im not sure.
Never press 29 or 73, 29 bricks your phone, 73 erases all files!
HERE is a thread on a cell phone forum with more info. The second page has a complete listing of functions in the test mode.
Also at that link, there is a way to get mobile web without paying the 5$ a month. It involves going to "menu > mobile web > 0 >enter lock code" Then enter new ip and port info.
Also, if you go to the settings menu, then press star, and enter 000000, you get the debug menu. select debug screen, and you see a bunch of numbers and letters, and one of the lines sars something like"T-63 D067-08" and the three digit number imeadiatelly following the D is an accurate measure of how good service you are getting, with 50 being great and 100+ being bad.
There is also a way to see your location with GPS, but it involves calling 922 which very often does not wwork and forwards you to 911. I will not post it, but it is ouy there on google.
Note: These haxorings work with many verizon samsung phones, not just the a670.