A User Equipment (UE) communicates with one or both of a first 3GPP core network and a second 3GPP core network over one or both of a 3GPP access and a non-3GPP access. The communication includes: receiving, from the first 3GPP core network, a reject message; and searching for another suitable cell or another suitable Access Point (AP), when the reject message is received over the 3GPP access or the non-3GPP access and the UE is registered with the first 3GPP core network or the second 3GPP core network over the 3GPP access or the non-3GPP access.