I have 2 lines, the first line ends in xxx-xxx-xx61, the sencond line ends in xxx-xxx-xx19. The first number is my line, and unfortunately my line is not able for an upgrade. The second number however is eligible for an upgrade. Will I be able to purchase the iPhone 3G at $199 with the second line and swap sim cards? While being able to also put the iPhone rate plan on my line?