I2 architecture VPC-routed case

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I2 architectureVPC-routed case

• Henning Schulzrinne

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Notes

• The drawing only reflects VPC-routed case
• Can also imagine having call server directly
  contact ESGW
• use DNS to determine appropriate ESGW
• might be several (e.g., several different
  operators)
• assumes business relationship of VSP with one or
  more ESGW operators

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In-band location
looks up location allocates ES
routes all 911 calls to VPC
provides in-band location
CAMA, SS7
handles contingency routing performs URI-to-trunk
mapping
SIP
SR
call server
CAMA
VSP V1
ESGW operator E1 may use MGCP or H.248 internally
E2 ESQK location
provides out-of-band location
ESGW operator E2
retrieves location information for call
VSP V2
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Out-of-band location
looks up location allocates ES
provides in-band location
handles contingency routing performs URI-to-trunk
mapping
SR
call server
SIP
VSP V1
ESGW operator E1 may use MGCP or H.248 internally
E2 ESQK location
provides out-of-band location
ESGW operator E2
retrieves location information for call
inserts location in redirect response
VSP V2
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Assumptions on relationship

• Call server is operated by VSP
• it is configured to contact contracted VPC for
  all emergency calls
• each VSP (typically) contracts with one VPC
  operator
• VSPs are often national in their footprint
• ESGW operators can be regional
• similar to SR operators today
• Thus, each VPC operator contracts with multiple
  ESGW operators
• and a single ESGW can be reached from multiple
  VPC operators