Today is a great day in the USA. Wireless Number Portability has arrived! I wrote about this last year and am glad that we have finally arrived to the point where number portability is now doable. So what is number portability? Well, effective today, you can change mobile phone provider without having to worry about changing your phone number. For example, if your phone number is (646) 555 1212, you can still keep the same number but choose between different mobile phone providers. An added extra is that you can also take your land-line phone number and port it to a mobile phone line. What’s the catch? Mobile phone operators sometimes work on different networks: GSM, CDMA, or TDMA. If you are switching between companies that are using different networks, you might have to change phone. If you are switching between GSM providers, all you may have to do is change your SIM card. If you are using a CDMA or TDMA provider, you might have to go to the store to get your phone reprogrammed with the new number. If you are still under contract with a provider, some penalty fees will be assessed. Make sure that you are…