Can I use my existing SIM card from another carrier with UNREAL Mobile? May 04, 2020 21:43 Updated Follow No, if you are going to use the UNREAL Mobile GSM. BUT, don't fret, your UNREAL Mobile SIM card and shipping are completely free when you order your first month of service. Was this article helpful? 0 out of 0 found this helpful Have more questions? Submit a request Return to top Related articles GSM: Device Compatibility Check Does UNREAL Mobile allow me to bring my own phone? Phones that are compatible with our LTE SIMs What is a Sprint eligible phone (BYOP Requirements) How do GSM Unlocked phones work?