Among other things described, a method of wireless communication includes transmitting, from a base station of a cell, to a user device requesting to camp on the cell, a message comprising a first field, wherein the first field is indicative of availability of another type of radio access technology (RAT) core network for communication via the base station, including, in the message, a second field whose value indicates that the user device is disallowed to access the another type of RAT core network, providing, when the user device is disallowed to camp on the cell, additional information regarding whether other intra-frequency cells that support the another type of radio access technology (RAT) core network are available for the user device to reselect.