3G UNLOCKED USB MODEM FOR GSM AND AT&T The Model 4596 lets you use AT&T 3G service without making an expensive long-term commitment. The modem is activated by plugging in a standard SIM card from AT&T. Unlike other modems, the Model 4596 is not locked to a specific service provider and can use a data SIM from services around the world. A change to the service provider is accomplished by simply sliding out one provider's SIM and replacing it with another provider's SIM. It takes only seconds and maximizes flexibility in using data plans.