Call Phases

MOBILE ORIGINATED CALL MS

BTS

Sdcch block ch_request (rach)

MSC

BSC

ch_activation

sdcch seiz att sdcch busy att ghost ccch res

ch_activation_ack

sdcch_assign

ch_required

VLR succ seiz orig succ seiz term sdcch call re est sdcch emerg call succ sdcch sms est uns. sdcch sms est sdcch loc upd

imm_assign_com

imm_assign (agch) cm_serv_req (sdcch)

est_indication

cr (cr_serv_req)

ua (sdcch)

process_access_req

authentication_req (sdcch) authentication_response (sdcch)

encr_com

cip_mod_com(sdcch)

cip_mod_comp (sdcch)

authenticate

cc (auth_req) dt1 (auth_res)

auth_res set_cip_mod

dt1(cip_mod_com)

dt1(cip_mod_comp) access_req_acpt

Sdcch to tch

tmsi_real_com tmsi_ral_complete

tmsi_real_comp

Setup (sdcch)

dt1 (setup)

call_proceeding (sdcch) phy_contxt_req

tmsi_ack send_info_for_og_call

dt1(call_proceeding)

complete_call

dt1(assign_req)

phy_contxt_confirm

Tch block

forward_new_tmsi

tmsi_real_com

tch request tch norm seiz tch req rej lack + a_bsc

ch_activation ch_activation_ack assign_command (sdcch) sabm (facch)

establish_indication

a_msc

ua (facch) assign_complete (facch)

dt1(assign_comp) ch_rel

ch_rel_ack

dt1(alerting)

alerting (facch) dt1(connect) connect (facch) connect_ack (facch) alerting (facch) connect (facch)

dt1 (connect_ack) dt1 (alerting) dt1 (connect) dt1(connect_ack)

connect_ack (facch)

PREPAID

MS

BTS

BSC

MSC

VLR

meas_report (facch) meas_report/result disconnect (facch)

dt1(disconnect) dt1(release)

release (facch)

b_msc release_complete (facch)

dt1(release_comp) dt1(clear_com)

ch_release (facch) deactivate_sacch disc (facch) ua (facch) rel_indication

b_bsc

rf_ch_rel rf_ch_rel_ack dt1(clear_comp) rlsd (sccp_rel) rlc (sccp_rel_ack)

Legend: Radio access part Establishment part Ciphering and encryption part call setup Tch seized Conversation part logical channel: tch Release by MS MS starts listening to bcch again

MOBILE TERMINATED CALL MS

MSC

BSC

BTS paging_command

paging_request (pch) channel_request (rach)

channel_required

udt (paging) sdcch seized att sdcch busy att ghost ccch res

channel_activation channel_activation_ack

sdcch assign

immediate_assign_com

immediate_assign (agch) sabm (paging_res sdcch)

establish_indication

succ seiz orig succ seiz term sdcch call re est sdcch emerg call succ sdcch sms est sdcch loc pd

cr (paging_response)

ua (sdcch) authentication_request (sdcch) authentication_response (sdcch) identity_request (sdcch) identification_response (sdcch) encryption_command

ciph_mode_com (sdcch)

ciphering_mode_complete (sdcch) setup (sdcch) call_proceeding (sdcch)

cc (authentication_req) dt1 (auth_res) dt1 (identity_req) dt1 (iden_res) dt1 (ciph_mode_com) dt1(ciph_mode_comp) dt1 (setup) dt1(call_proceeding)

physical_context_req

dt1 (assign_req)

physical_context_confirm channel_activation channel_activation_ack assignment_command (sdcch) sabm (facch)

tch request tch req rej lack tch norm seiz + a_bsc

establish_indication

a_msc

ua (facch) assignment_complete (facch)

dt1 (assign_complete)

channel_release channel_release_ack alerting (facch)

dt1 (alerting)

connect (facch)

dt1 (connect)

connect_ack (facch) meas_rep (sacch)

meas_report/result

disconnect (facch)

dt1(disconnect)

release (facch) release_complete (facch) channel_release (facch) disc (facch) ua (facch)

dt1(connect_ack)

deactivate_sacch

dt1(release) dt1(rel_complete) dt1(clear_command)

b_msc

MS

MSC

BSC

BTS release_indication

b_bsc

rf_channel_rel rf_channel_rel_ack

dt1(clear_complete) rlsd (sccp_released) rlsd (sccp_released_ack)

Legend:

Paging part

Radio access part

Establishment part Ciphering and encryption part call setup Tch seized

Conversation part logical channel: tch

Release by MS

MS starts listening to bcch again

BSC INTERNAL HANDOVER, INTER CELL MS

BTS 1

BSC

BTS 2

meas_rep (sacch)

measurement_result

MSC

handover decision

ch_activation ch_activation_ack botta bosa bitta bisa (ctta) (csa)

ho_command

ho_command(facch) ho_access (facch)

ho_detect

physical_info (facch) sabm (facch)

establish_indication bish bosh (csh) (mish) (mosh)

ua (facch_ ho_complete (facch) rr (facch) ho_complete rf_channel_release rf_channel_release_ack

Legend: Ho measurements and decisions

Tch reservation and activation in BTS 2

Signalling on facch-tch in BTS 1

Signalling on facch-tch in BTS 2 connection

Tch release in BTS 1

dt1(ho_performed)