Originally Posted by daveowns
You can do this with an iPhone though?
He is saying Red Pocket will do this for the droid 3. This true?
An iPhone that runs on Verizon's network, instead of ATT's, does not have a GSM radio at all and cannot accept a SIM card of any type. It cannot ever be used on anything but CDMA, so no - you cannot do anything to a Verizon version iPhone to make it work on ATT or T-Mobile or any other GSM network.
You could sell it or trade such a phone and get an GSM iPhone instead.
A Red Pocket SIM card would allow your Droid3 to run on the ATT 3G GSM network, sure, if your Droid3's radio (software) would allow it, but that is not allowed by Verizon's design of the Droid3's radio, on purpose. You can change the default radio software that the Droid3 shipped with, but that is complicated and beyond my ability to describe to you here. If you got a Droid3 from like China, as shipped to work in the Chinese market, a Red Rocket SIM card would probably work to enable ATT GSM, but the phone would have Chinese text...