@startuml "TD_VoLTE_EMC_INT_REG_01.png"
!include etsi-style.iuml
!pragma teoz true
'
'Figure : IMS Emergency Registration (success)
'
''title Figure : IMS Emergency Registration (success)
'
participant "UE A"
box "EPC A" #LightBlue
  participant PGw
  participant PCRF
end box
box "IMS A" #LightBlue
  participant "P-CSCF"
  participant "I-CSCF"
  participant "S-CSCF"
  participant "HSS"
end box
'
rnote right  "UE A"         : Gm
& rnote right "PCRF"        : Rx
& rnote right "PGw"         : Gx
& rnote right "P-CSCF"      : Mw
& rnote right "I-CSCF"      : Mw
& rnote left  "S-CSCF"      : Mw
& rnote left  "HSS"         : Cx
'

"UE A"     ->   "P-CSCF"    : REGISTER(Contact: *sos)
"P-CSCF"   -->  "PCRF"      : AAR 
"PCRF"     -->  "P-CSCF"    : AAA 
&"P-CSCF"  ->   "I-CSCF"    : REGISTER
& "I-CSCF" ->   "HSS"       : UAR
"HSS"      ->   "I-CSCF"    : UAA
"I-CSCF"   ->   "S-CSCF"    : REGISTER
& "S-CSCF" ->   "HSS"       : MAR
"HSS"      ->   "S-CSCF"    : MAA
& "S-CSCF" ->   "I-CSCF"    : 401 Unauthorized
& "I-CSCF" ->   "P-CSCF"    : 401 Unauthorized
& "P-CSCF" ->   "UE A"      : 401 Unauthorized
"UE A"     ->   "P-CSCF"    : REGISTER(Contact: *sos)
& "P-CSCF" ->   "I-CSCF"    : REGISTER
& "I-CSCF" ->   "HSS"       : UAR
"HSS"      ->   "I-CSCF"    : UAA
"I-CSCF"   ->   "S-CSCF"    : REGISTER
& "S-CSCF" ->   "HSS"       : SAR
"HSS"      ->   "S-CSCF"    : SAA
& "S-CSCF" ->   "I-CSCF"    : 200 OK
& "I-CSCF" ->   "P-CSCF"    : 200 OK
& "P-CSCF" ->   "UE A"      : 200 OK
"UE A"     <--> "P-CSCF"    : IMS Emergency signalling \n possible over Emergency Bearer
@enduml