MGCP

  1. Media gateway control protocol (MGCP)
    1. Signal types
    2. Events/signals
    3. Event actions
    4. MGCP command parameters
    5. MGCP commands

Media gateway control protocol (MGCP)

  • RFC 2705
  • uses SDP to describe sessions: IP, UDP ports, RTP profile
  • manages MGs that bridge between IP and PSTN

Signal types

  • on/off (OO): active if not disabled
  • timeout (TO): active until disabled or timeout
  • brief (BR): short signal, stops itself

Events/signals

  • off-hook (Hd): OO
  • on-hook (Hu): OO
  • dial-tone (DL): TO (120s)
  • ringing (Rg): TO (30s)
  • flash hook (Hf): BR
  • busy tone (Bz): OO
  • answer tone (Aw): OO
  • call-waiting tone (Wt): TO (30s)
  • caller ID(ci(ctring)): BR
  • modem tone detected (Mt)
  • fax tone detected (Ft)
  • network congestion tone (Cg): TO
  • intercept tone (It): OO
  • wink (Wk): BR
  • wink off (Wko): BR
  • DTMF digit 8 (dtmf 8): BR
  • MF digit 9 (mf 9): BR
  • play announcement (Ann): TO
  • load Java script (Java): TO

Event actions

  • notify immediately (N): default
  • accumulate (A)
  • treat according to digit map (D)
  • swap (S)
  • ignore (I)
  • keep signal active (K)
  • embedded notification request (E):
    • set in requested evenets
    • action fired on event
    • R: Hd(E(R<requested_events>), S(<signal_requests>))

MGCP command parameters

  • Call-ID: globally unique
  • Notified Entity (N): where to send notifications
  • Local Connection Options (L): encoding method, packetization period, BW, ToS, AEC
  • Mode (M): full-duplex, receive-only, send-only, inactive, loopback
  • Remote Connection Descriptor (RC)
  • Connection ID (I)
  • Requested Events (R): format = “R: event(action)” (e.g., “R: hu(N))
  • Signal Requests (S)
  • Request ID (X)
  • Observed Events (O)
  • Detect Events (T): events in quarantine
  • Local Connection Descriptor (LC)
  • Connection Parameter (P)
  • Restart Method (RM): graceful, forced, restart (≡ back in service), disconnected (≡ trying to reconnect)
  • Restart Delay (RD): seconds
  • Bearer information (B): a-law, µ-law

MGCP commands

  • CreateConnection (CRCX): Call-ID, N, L, M, RC
  • ModifyConnection (MDCX):
    • Call-ID, N, L, M, RC, I
    • change encoding, packetization period, AEC
  • DeleteConnection (DLCX)
  • NotificationRequest (RQNT): R, S, N, X
  • Notification (NTFY): N, X, O
  • AuditEndpoint (AUEP): endpoint list, N, R, digit map, S, X, I, T, L
  • AuditConnection (AUCX): Call-ID, N, L, M, RC, LC, P
  • RestartInProgress (RSIP):
    • endpoint ID, RM, RD
    • notify about endpoint being in/out of production
  • EndpointConfiguration (EPCF): B