plete Ciphering Mode Complete Setup Setup Call Confirmed Call Confirmed Assignment Command Assignment Command Assignment Complete Assignment Complete Alerting Alerting Connect Connect Connect Acknowledgement Connect Acknowledgement MTC : Mobile Terminated Call MOC : Mobile Originated Call Figure 2.62 MOC and MTC connection establishment messages SMS Establishment Phases Phase 6 covers the SMS establishment signalling over a dedicated TCH and data request from the Phase 7 covers the SMS establishment signalling over a dedicated SDCCH. Phase 8 covers the ciphering signalling (from Cipheringmode_command to Cipher- ing.mode_complete); it is a sort of 'bracket' inside phase 2. The dedicated channel can be an SDCCH or a TCH. Handover Phases Phase 9 covers the external handover signalling of the source side on an SDCCH and a TCH. Phase 10 covers the internal intracell handover signalling of the source side on an SDCCH and a TCH. Phase 11 covers the internal intercell handover signalling for the source side on an SDCCH or a TCH. Phase 12 covers the external handover signalling for the target side on an SDCCH and a TCH. Phase 13 covers the internal intracell handover signalling for the target side on an SDCCH and a TCH. Phase 14 covers the internal intercell handover signalling for the target side on an SDCCH or a TCH. Phase 15 covers the MM signalling between the MS and the MSC during conversation on a TCH. The phases relevant to a call will now be highlighted along with an illustration of a mobile originated call scenario (Figure 2.63). The mobile terminated call uses the same signalling chart with some differences as compared to the mobile originated call: Channel request Channel required Channel activation RR connection Channel activation acknowledgement establishment Immediate Assignment Command Phase 1 Immediate Assignment Command Establish Indication Service Request Authentication request Authentication request Authentication request Authentication Phase 2 Authentication response Authentication response Authenticat