Understanding the SRX Series Integrated Convergence Services Media Gateway

This topic describes the SRX Series media gateway (SRX Series MGW) and the parameters used to configure it. You must configure the media gateway component of the SRX Series MGW only if you plan to configure trunks for it to allow the peer call server to route calls out them as well as its own trunks.

Integrated Convergence Services is composed of hardware and software on the SRX210 or SRX240 device. It includes SRX Series MGW and SRX Series survivable call server (SRX Series SCS) components. The SRX Series MGW functionality is used predominantly when the peer call server is available to provide call handling and call routing services for analog phones and faxes and SIP phones at the branch.

Note: When the peer call server is unreachable, the SRX Series SCS assumes control and takes on the role of the peer call server, and the SRX Series MGW performs lesser functions.

When the SRX Series MGW is in control:

• It converts calls from analog stations to digital signals before it routes them over the IP WAN as VoIP calls to the peer call server for processing.
• It converts calls for analog stations routed to it from the peer call server from digital signals to analog ones. After it converts a call from digital to analog, the SRX Series MGW forwards the call to the correct analog station, matching the called number to the station extension.
• SIP phones register directly to the peer call server. Because the transmission is digital, the SRX Series MGW does not need to intercede as a gateway on behalf of SIP calls.

To configure the SRX Series MGW, you specify the following information:

• A name for the SRX Series MGW.
• The name of the peer call server that provides call handling and routing services. The SRX Series MGW uses information about the peer call server to communicate with it.
• SIP protocol information.
  • port—The number used for the port, or communications endpoint, for the SIP protocol. The well-known SIP port 5060 is used by default.
  • transport—The transport used for the SIP protocol. The default transport is UDP.
    • (UDP) User Datagram Protocol. A single UDP packet carries a SIP request or response. SIP does not support fragmentation, so UDP SIP messages must be smaller than the MTU size of interfaces on nodes the packet traverses.
    • (TCP) Transport Control Protocol. Because TCP can support messages of arbitrary size, it supports larger messages and provides reliability and congestion control.
    • (TLS) Transport Layer Security. TLS provides for security and data integrity of communications over the Internet Protocol (IP).
• The name of the SRX Series MGW dial plan. To use SRX Series MGW trunks with trunk access codes to enable the peer call server to route calls out them, you must configure a dial plan. You can create a single dial plan that contains entries for the SRX Series MGW and the SRX series survivable call server (SRX Series SCS), or you can create separate dial plans for them.

Related Topics

• Example: Configuring an Integrated Convergence Services Media Gateway and Trunks
• SRX Series Integrated Convergence Services Media Gateway Overview
• Understanding the Media Gateway Peer Call Server for SRX Series Integrated Convergence Services
• Understanding Integrated Convergence Services Media Gateway Trunks and Dial Plans