WiFiRanger routers with integrated modems are certified for use on the AT&T and T-Mobile networks. Verizon certification is in process. If your SIM is already activated on either the AT&T or T-Mobile networks and are on a hotspot data plan, it likely that it will work when inserted into an integrated WiFiRanger LTE modem. However, WiFiRanger does not guarantee that any user-provided SIMs and plans will work in its products. WiFiRanger does market data plans from Freedom Go that are certified and guaranteed to work with integrated WiFiRanger LTE modems on the ATT network. Learn more about these plans here.