 @startuml "TD_VoLTE_ECO_INT_INI_09.png"


!include etsi-style.iuml
!pragma teoz true
'
'Figure: Emergency Session Establishment, PSAP in same IM CN subsystem
'
''title Figure : Emergency Session Establishment, PSAP in same IM CN subsystem
'
participant "UE A"
'box "EPC A" #LightBlue
'  participant PGw
'  participant "PCRF"
'end box
box "IMS A" #LightBlue
  participant "AS"
	participant "S-CSCF"
	participant "E-CSCF"
end box

	participant "PSAP"

rnote right  "UE A"         : Gm
& rnote right "AS"          : ISC
& rnote right "S-CSCF"      : Mw
& rnote right "E-CSCF"      : Mm

'
"UE A"     -->   "AS"    : Emergency
& "AS"     ->   "S-CSCF"    : INVITE
'"S-CSCF"   ->   "PCRF"    : AAR
'rnote over "PCRF", PGw #FFAAAA: Policy decision
'"PCRF"   ->   "PGw"       : RAR
'rnote over "PCRF", PGw  #FFAAAA: Installation of the Session Bearer
'"PGw"      ->   "PCRF"    : RAA
'& "PCRF" ->   "S-CSCF"    : AAA
'"PGw"      ->   "PCRF"    : CCR
'& "PCRF" ->   "S-CSCF"    : RAR
' "S-CSCF"  ->   "PCRF"    : RAA
'& "PCRF" ->   "PGw"       : CCA
 "S-CSCF" ->   "E-CSCF"    : INVITE
& "E-CSCF" ->   "PSAP"  : INVITE
"PSAP" ->   "E-CSCF"    : 183 Session Progress\n(SDP answer)
& "E-CSCF" ->   "S-CSCF"    : 183 Session Progress\n(SDP answer)
'& "S-CSCF" ->   "PCRF"    : AAR
'& "PCRF" ->   "PGw"       : RAR
'rnote over "PCRF", PGw #FFAAAA: Modification of the Session Bearer 
'"PGw"      ->   "PCRF"    : RAA
'& "PCRF" ->   "S-CSCF"    : AAA
"S-CSCF"   ->   "UE A"      : 183 Session Progress\n(SDP answer)
"UE A"     <--> "PSAP"  : Early Media
"PSAP" ->   "E-CSCF"    : 180 Ringing
& "E-CSCF" ->   "S-CSCF"    : 180 Ringing
&"S-CSCF"   ->   "UE A"      : 180 Ringing
"PSAP" ->   "E-CSCF"    : 200 OK
& "E-CSCF" ->   "S-CSCF"    : 200 OK
& "S-CSCF"   ->   "UE A"      : 200 OK
"UE A"     ->   "S-CSCF"    : ACK
& "S-CSCF" ->   "E-CSCF"    : ACK
& "E-CSCF" ->   "PSAP"  : ACK
"UE A"     <--> "PSAP"  : Media Exchange
@enduml
