Section: 4.7.1.7b Intersystem change from S1 mode to A/Gb mode or S1 mode to Iu mode for eCall only MS capable of eCall over IMS
Content: If an eCall only MS (as determined by information configured in USIM) capable of eCall over IMS returns from S1 mode to A/Gb or Iu mode, the MS shall: a) if timer T3444 is running, start timer T3242 with the time left on timer T3444, and stop timer T3444; b) if timer T3445 is running, start timer T3243 with the time left on timer T3445, and stop timer T3445; c) if the MS is attached for GPRS services only and timer T3444 or timer T3445 is running: - perform a combined routing area updating procedure with IMSI attach if the network operates in network operation mode I; and - perform a routing area updating procedure and a location area updating procedure if the network operates in network operation mode II; and d) if the MS is attached for both GPRS services and non-GPRS services and timer T3444 or timer T3445 is running: - perform a combined routing area updating procedure if the network operates in network operation mode I; and - perform a routing area updating procedure and a location are updating procedure if the network operates in network operation mode II. NOTE: Timers T3444 and T3445 are specified in 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [120].