Can I use iPhone and iPad for one account? November 25, 2020 05:51 Updated You can use both iPhone and iPad for one account. Related articles An error which says "Failed to retrieve the device certification by communicating with Apple" has appeared. And I failed to login. Can I use more than one device with the same OS for one account? 5.Useful Functions Failed to communicate with server. (CE001/CE008) An error message of concurrent connection prohibited (W002) appears.