LTE UE Modes of Operation

From 3GPP TS 24.301, section 4.3:

UE mode of operation

A UE attached for EPS services may operate in one of the following operation modes:

- PS mode of operation: the UE registers only to EPS services;

- CS/PS mode 1 of operation: the UE is CS fallback capable and configured to use CS fallback, and non-EPS services are preferred. The UE registers to both EPS and non-EPS services; and

- CS/PS mode 2 of operation: the UE is CS fallback capable and configured to use CS fallback, and EPS services are preferred. The UE registers to both EPS and non-EPS services.