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    Understanding the Functions of the SRX220 Services Gateway with Integrated Convergence Services

    The SRX220 Services Gateway with Integrated Convergence Services functions as follows:

    • IP phones are either directly connected to a PoE port on the SRX220 Services Gateway with Integrated Convergence Services, or connected to a separate switch with PoE.
    • SIP trunks connect to the SRX220 Services Gateway with Integrated Convergence Services over WAN interfaces (usually with T1 or Ethernet ports).
    • Analog telephones and fax machines are directly connected to the SRX220 Services Gateway with Integrated Convergence Services through Foreign Exchange Station (FXS) interfaces.
    • The telephone exchange or PSTN central office is directly connected to the SRX220 Services Gateway with Integrated Convergence Services through Foreign Exchange Office (FXO) or T1/E1 interfaces.
    • The media gateway converts analog signals from FXS and FXO ports and digital time-division multiplexing (TDM) signals from T1/E1 ports to VoIP packets and sends them to the network after processing through Junos OS secure routing and firewall flows. Similarly, the media gateway receives forwarded VoIP packets from the network, converts them into analog signals or digital TDM signals, and sends them across the appropriate interface.
    • The media gateway also provides power failover support in the event of power loss, by providing a hardware relay between the built-in FXS2 port and FXO1 port, which automatically connects the two ports when the media gateway loses power.

      Note: The 2-Port FXS/2-Port FXO Mini-PIM, the 4-Port FXO Mini-PIM, and the 4-Port FXS Mini-PIM do not support failover relay between any of the FXS and FXO ports.

    • The SRX220 Services Gateway with Integrated Convergence Services may also interconnect two SIP trunks (for example, a service provider SIP trunk and an enterprise internal SIP trunk). In this case, the media gateway acts as a back-to-back user agent (B2BUA) and ensures security and quality of service (QoS) for the calls.
    • Telephony interface expansion available through Mini-PIM interface card options includes:
      • 2-Port FXS/2-Port FXO Mini-PIM
      • 4-Port FXO Mini-PIM
      • 4-Port FXS Mini-PIM
      • T1/E1 mPIM with support for both flexible T1-channel-associated signaling (CAS) (loop start and wink start) and T1-ISDN PRI

      Note: For more information on Mini-PIMs, see the SRX Series Services Gateways for the Branch Physical Interface Modules Hardware Guide.


    Published: 2010-10-05