Apparatuses and methods for mobility management (mm) congestion control

A User Equipment (UE), comprising:

• a wireless transceiver, configured to perform wireless transmission and reception to and from a first service network located in a first Public Land Mobile Network (PLMN) via one of a 3rd Generation Partnership Project (3GPP) access and a non-3GPP access, and a second service network located in a second PLMN via the other of the 3GPP access and the non-3GPP access;
• and
• a controller, configured to start a first Mobility Management (MM) back-off timer in response to a first MM procedure with the first service network being rejected, determine whether the first PLMN and the second PLMN are equivalent PLMNs in response to starting the first MM back-off timer, and initiate a second MM procedure with the second service network via the wireless transceiver when the first MM back-off timer is running, in response to determining that the first PLMN and the second PLMN are not equivalent PLMNs.