A:AnswerYes, but one at a time. If you are using SIM 1, and someone calls you to SIM2, the caller will hear the number is in occupied-in use. You can only use data in only one SIM.
A:AnswerU.S. Cellular may be using CDMA network, which means that it would not be compatible with this phone with GSM network capability. Check with U.S. Cellular on whether the Prepaid SIM card is for a GSM or a CDMA network.