@startuml "TD_VoLTE_ECO_INT_INI_07.png"


!include etsi-style.iuml
!pragma teoz true
'
'Figure: Emergency Session Establishment, PSAP in the PSTN
'
''title Figure : Emergency Session Establishment, PSAP in the PSTN
'
participant "UE A"
box "EPC A" #LightBlue
  participant PGw
  participant "PCRF"
end box
box "IMS A" #LightBlue
	participant "P-CSCF"
	participant "E-CSCF"
	participant "BGCF"
end box

	participant "PSAP"

rnote right  "UE A"         : Gm
& rnote right "P-CSCF"      : Mw
& rnote right "E-CSCF"      : Mi
& rnote right "PCRF"        : Rx
& rnote right "PGw"         : Gx

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