A slave device comprising: a connectivity circuit configured to receive first network access information, NAI, from a first external device (620, 700) via a first communication link and second NAI from a second external device (640, 700) via a second communication link, to relay first data to the first external device (620, 700) via the first communication link and second data to the second external device (640, 700) via the second communication link, and to receive third data from the first external device (620, 700) via the first communication link and fourth data from the second external device (640, 700) via the second communication link; a memory configured to store the first NAI associated with a first communication service for the first external device (620, 700), and to store the second NAI associated with a second communication service for the second external device (640, 700); a communication processor (632, 710) configured to select one of the first NAI and the second NAI, and to access the first communication service or the second communication service over a public wireless network, PWN, using the selected one among the first NAI and the second NAI; and an application processor configured to control the communication processor (632, 71) and the connectivity circuit, and to control a process on information provided from the communication processor (632, 710) and/or the connectivity circuit, wherein the slave device does not include a subscriber identification module, SIM, the slave device is configured to receive the first data from the first communication service over the PWN, characterized in that: the slave device is configured to generate updated first NAI while the first communication service is connected, the slave device is configured to generate updated second NAI while the second communication service is connected, the slave device is configured to synchronize the updated first NAI between the slave device and the first external device (620, 700) via the first communication link, and the slave device is configured to synchronize the updated second NAI between the slave device and the second external device (640, 700) via the second communication link. a connectivity circuit configured to receive first network access information, NAI, from a first external device (620, 700) via a first communication link and second NAI from a second external device (640, 700) via a second communication link, to relay first data to the first external device (620, 700) via the first communication link and second data to the second external device (640, 700) via the second communication link, and to receive third data from the first external device (620, 700) via the first communication link and fourth data from the second external device (640, 700) via the second communication link; a memory configured to store the first NAI associated with a first communication service for the first external device (620, 700), and to store the second NAI associated with a second communication service for the second external device (640, 700); a communication processor (632, 710) configured to select one of the first NAI and the second NAI, and to access the first communication service or the second communication service over a public wireless network, PWN, using the selected one among the first NAI and the second NAI; and an application processor configured to control the communication processor (632, 71) and the connectivity circuit, and to control a process on information provided from the communication processor (632, 710) and/or the connectivity circuit, wherein the slave device does not include a subscriber identification module, SIM, the slave device is configured to receive the first data from the first communication service over the PWN, characterized in that: the slave device is configured to generate updated first NAI while the first communication service is connected, the slave device is configured to generate updated second NAI while the second communication service is connected, the slave device is configured to synchronize the updated first NAI between the slave device and the first external device (620, 700) via the first communication link, and the slave device is configured to synchronize the updated second NAI between the slave device and the second external device (640, 700) via the second communication link.