A:Answer Hi Mixxer,
Thank you for reaching out to us. I appreciate your inquiry about whether the Galaxy S21 Ultra (Unlocked) works with Boost Mobile. Unlocked phones by Samsung works on multiple networks, give you the freedom to switch carriers any time, and make sure that you have a compatible SIM card. Please note that sim cards must be compatible with the area's available networks. International calling, data services, and coverage vary by the network provider. Contact provider for details.
You may visit our website for more information about unlocked phones: https://www.samsung.com/us/mobile/phones/unlocked-by-samsung/.
You may also vivit our website under "Learn about Unlocked phones":
https://www.samsung.com/us/smartphones/galaxy-s21-5g/buy/galaxy-s21-fe-5g-128gb-unlocked-sm-g990uzadxaa/
Should you need more assistance, you may reach us via the following for immediate support:
1. Samsung Community: https://us.community.samsung.com/t5/Samsung-Community/ct-p/us
2. Facebook Messenger: http://m.me/samsungsupport
3. Twitter: https://twitter.com/messages/compose?recepient_ id=18768513
Reference Number: 1144229407
Thank you for choosing Samsung. Have a great day!
^Chrystel