@startuml "TD_VoLTE_EMC_INT_ATT_01.png"
!include etsi-style.iuml
!pragma teoz true
'
'Figure : Emergency Network Attachment with USIM and Establishment of the Emergency Bearer
'
''title Figure : Emergency Network Attachment and Establishment of the Emergency Bearer
'
participant "UE A"
box "EPC A" #LightBlue
  participant MME
  participant SGw
  participant PGw
  participant PCRF
end box
box "IMS A" #LightBlue
  participant "P-CSCF"
  participant "HSS"
end box
'
rnote right  "UE A"         : Gm
& rnote right "MME"         : S6a
& rnote right "PGw"         : Gx
& rnote right "PCRF"        : Rx
'
rnote over "UE A", SGw  #FFAAAA: Attachment to E-UTRAN
"UE A"     ->   "MME"       : Establish Emergency IP-CAN\nSession Request
"MME"      ->   "HSS"       : ULR
"HSS"      ->   "MME"       : ULA
"PGw"      ->   "PCRF"      : CCR(with IMSI)
rnote over "PGw", "PCRF"  #FFAAAA: Policy Decision
"PCRF"     ->   "PGw"       : CCA
"MME"      ->   "UE A"      : Establish Emergency IP-CAN\nSession Response
"UE A"     <--> "P-CSCF"    : Emergency call possible over Emergency Bearer

@enduml