Electronic devices may have multiple wireless integrated circuits such as first and second baseband processor integrated circuits. The first baseband processors may be used exclusively for handling packet switched traffic, whereas the second baseband processor may be used exclusively for handling circuit switched traffic. Radio-frequency front end circuitry may be used to couple multiple antennas to the baseband processors and associated radio-frequency transceivers. The first baseband processor may be coupled to a first universal integrated circuit card (UICC) storing a first subscriber profile, whereas the second baseband processor may be coupled to a second UICC storing a second subscriber profile. The first baseband processor may be used to support any desired circuit switched radio access technology, whereas the second baseband processor may be used to support any desired packet switched radio access technology.