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 both AT&T and Millenicom (T-Mobile) that are certified and guaranteed to work with integrated WiFiRanger LTE modems. Learn more about these plans here.