Originally Posted by freewheeling
I don't understand. I used the original modem and SIM card and it didn't work. What do you mean "modem radio on the card"? Which card? The SIM card?
There has to be something that ids the motherboard, though, because I've tried using the original SIM and modem.
That was "modem/radio" because both are on the same card - in fact, within the same SoC on the card.
It is the only mini-PCIe shaped card in the device.
The Subscriber Information Card (SIM) also holds identifying information **of the M2M (Machine-to-Machine)** 3G account.
There is also indemnifying information in the Kindle's flash memory (that identifies the Kindle and the Wifi M2M account).
One of those things is the MAC address used by the Wifi connection.
When you see "Kindle MAC address" phrase in this forum, it refers to the one associated with the Kindle and its Wifi (the one stored in the Kindle's flash).
The system image of the 3G modem/radio is a locked, signed image. There is no changing what is in that, only what is on the SIM card.