Hi, the problem was unrelated to the SIM card, and occurred with Hologram and other SIM cards.
The problem was that I was not properly closing the socket I was using, so after 7 such failures to close the socket, there were no more available and the +CME ERROR would occur. Resetting the Nova (AT+CFUN=15) would fix the problem but, of course, properly closing the socket (AT+USOCL) is the proper solution.