The sim cards are different so that’s why I was wondering if that’s possible since I cant just switch those
If I have an old republic wireless phone that still works am i able to reactivate it and switch my number back to that phone?
Yes, as long as the phone is not the old Defy.
The E1, E2, G1,G3, X1 and X2 phones can all be reactivated and your number transferred. Activating the phone as a replacement/upgrade will move the phone number from one Republic phone to another Republic phone.
the Legacy SIMs do not deactivate like the 3.0 ones do they are still good and ready for use when the phone is reactivated (They are linked to the phone and why they need to stay with the phone)
do note when you activate the old phone you are deactivating your current 3.0 phone and that process kills the SIM so in order to reactivate you will need a new SIM (which currently are GSM only)