Many modern mobile phones support several RATs in one device such as Bluetooth, Wi-Fi, and GSM, UMTS, LTE or 5G NR.
[1] More recently, the term RAT is used in discussions of heterogeneous wireless networks.
[2] The term is used when a user device selects between the type of RAT being used to connect to the Internet.
This is often performed similar to access point selection in IEEE 802.11 (Wi-Fi) based networks.
Based on this measurement report provided by the mobile terminal, the network can initiate handover from one RAT to another, e.g. from WCDMA to GSM or vice versa.