I have to buy a new phone (my present phone is not repairable); I’m looking at phones on Amazon, if it says like below “International version, GSM only” will the phone work in US and is it compatible with Republic Wireless?
No. The phone you have described will not work with Republic Wireless. Republic Wireless supports Samsung Galaxy A21 with model # SM-A215U1.
From Samsung Galaxy A21 – Republic Wireless :
We support only the North American factory unlocked version of this phone, model number SM-A215U1. Models without the “1” are not compatible with Republic. Some vendors will list this phone by the Manufacturer’s Part Number (MPN): SM-A215UZKAXAA or SM-A215UZKAXAG.
If you’re unsure whether the phone you’re buying meets these requirements, we suggest contacting the seller directly to verify the information.
Please note: Samsung phones sold secondhand are often different versions that have had their software modified to mimic the factory-unlocked version. These phones may be misrepresented with the model number or MPN that we do support. However, these phones cannot be activated on our network and we cannot be responsible for misrepresented phones sold by third parties. If the product description you are considering includes a note that it will activate only on a GSM network, or if the seller indicates the phone will not activate on Sprint or Verizon, this is not the phone model that we support. Please make sure you are buying from a reputable seller.