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SIP Module |
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The CommuniGate Pro SIP module implements the SIP Internet protocols via
IP networks.
The module is used to receive Signal Requests from remote entities,
and to send Signals to remote entities.
The SIP protocol does not include the protocols required for actual data
transfer (media transfer protocols). Instead, it allows all participating parties to find each other
on the network, to negotiate the media transfer protocol(s) and protocol parameters,
establish the interactive real-time sessions, and to
manage those sessions (add new parties, close sessions, update session parameters, etc.).
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Session Initiation Protocol (SIP)
The CommuniGate Pro SIP Module implements the SIP protocol functionality.
The module uses TCP and UDP listeners to receive SIP request and response packets via these network protocols.
It also sends the response and request packets via the TCP and UDP network protocols.
The SIP module parses all received SIP packets, and uses the module subcomponents to
process the parsed packets. Request packets are submitted to the SIP Server subcomponent, to a new SIP Server
transaction or to an existing one.
The SIP Server component uses the Signal Module to process the request.
The responses generated with the Signal module are submitted to the SIP Server transaction, and the SIP Server sends
them back to the source of the SIP request.
The Signal module can send a Request to a different
SIP device or a SIP server.
The module uses the SIP Client subcomponent to create a SIP Client transaction.
This transaction is used to send a SIP Request via an Internet protocol,
and to process the Responses sent back.
SIP Request packets received with the SIP Module are submitted to the SIP Server subcomponent,
while SIP Response packets are submitted to the SIP Client subcomponent, with two exceptions:
- if no Client transaction can be found for a Response packet, the packet is relayed "upstream" by the SIP
Module itself, without using the Signal module.
- if no Server transaction can be found for an ACK Request, a SIP Client transaction is created to relay the
ACK Request "downstream".
The CommuniGate Pro SIP module supports UDP and TCP communications, and it also supports secure
(TLS) communications over the TCP protocol.
The CommuniGate Pro SIP module supports near-end and far-end NAT traversal,
enabling SIP communications for both large corporations with many internal LANs, as well as
for home users connecting to the Internet via "dumb" NAT devices.
The session initiation schema described above works correctly only if both parties can
communicate directly. If there is a firewall or a NAT device between the parties, direct
communication is not possible. In this case, the CommuniGate Pro SIP module builds and manages
the necessary media proxies, relaying not only the SIP protocol requests and responses,
but the actual media data, too.
SIP Transport Settings
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To configure the SIP module, use a Web browser to connect to the
CommuniGate Pro Server WebAdmin Interface, and open the SIP page in the Settings realm.
To configure the SIP module, you should have the Can Modify Settings access right.
The Transport panel allows you to configure the network-level options:
- Log
- Use this setting to specify the type of information about SIP packets and SP transport
the module should put in the Server Log. Usually you should use the Failure
(unrecoverable problems only), Major (session establishment reports),
or Problems (failures, session establishment and non-fatal errors) levels.
When you experience problems with the SIP module,
you may want to set the Log Level setting to Low-Level or All
Info: in this case the packet contents and other details will be recorded
in the System Log. When the problem is solved, set the Log Level setting
to its regular value, otherwise your System Log files will grow in size
very quickly.
The SIP module transport records in the System Log are marked with the SIPDATA tag.
Generic SIP information records have the SIP tag.
- UDP
- To configure the UDP transport, click the UDP listener link. The UDP Listener page will open.
By default, the SIP UDP port is 5060.
- Request Size Limit
- Use this option to specify the size for the largest UDP packet that can be sent withing your LAN and outside your LAN.
If the SIP module needs to deliver a packet and the protocol is not explictily specified, the SIP module uses the UDP protocol,
unless the packet size is larger than the specified limit. In the latter case the TCP protocol is used.
- TCP
- To configure the TCP transport, click the TCP listener link. The TCP Listener page will open. There
you can specify both secure and clear-text TCP ports. By default, the clear-text SIP TCP port is 5060, and the SIP TLS port is 5061.
- Input Channels
- Use this option to specify the maximum number of TCP communication channels the module can open. If the number is exceeded, the module
will reject new incoming TCP connections.
- Idle Timeout
- Use this option to specify when the SIP module should close a TCP communication channel if there is no activity on that channel. This helps
to reduce the resources used for TCP communication channels on large installations. On the other hand, some SIP clients may not function properly
if the server closes its TCP connection on a time-out.
Transaction Settings
- You can specify how the SIP Module handles SIP server and client transactions.
