its the 4G (aka iphone 4 [GSM])
(note GSM means it uses a SIM card and SIM tray where as the CDMA model does not.)
after researching i found that the external SIM adapter for two SIM cards has a micro-controller or flash memory on the adapter (i am guessing is is flash memory because when you plug it in you get the menu in SIM applications which i have not seen happnen on my phone or a couple of others (where they just have 1 SIM card and no adapter)
the menu is for changing the phone numbers, swapping the numbers round , swapping the sim cards round (you don't need to necessarily take them out and swap which trey they are in), change the time for the SIM card so you can delay when the sim will show the data even though it will be sent on the same day and similar time as when it is sent by the other person)
you can still check because you never know , but it is unlikely
also is there 'TTY' when you go into 'settings > phone'
ans do you have 'change voicemail password' when you go into 'settings > phone'
i am not sure if the jailbreak has changed the menu , you will see when you check the phone anyway
Kris