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SIP container settings

Use this page to configure the SIP container settings for Session Initiation Protocol(SIP). To view this console page, click Servers > Server Types > WebSphere application servers > server_name > SIP container settings > SIP container.


Maximum application sessions

Maximum number of SIP application sessions that the container manages. When the maximum is reached, no new SIP conversations are started. When the maximum is exceeded in a clustered environment, the server does not forward new dialogs until the number of application sessions no longer exceeds the maximum.

Application sessions are typically created by new incoming calls, but can also be created by other events. The application session count does not impact failover, but applies only to new sessions created as a result of incoming calls.

When application sessions are transferred from one application server to another due to failover, the active application server inherits the sessions created on the failed server. In addition, the servlet might create a new application session in the SIP container by calling SipFactory.createApplicationSession().

New application sessions created for events other than starting SIP conversations are not controlled by this setting. But all new application sessions are included when computing the maximum number of application sessions allowed. Thus, all active application sessions, including those not related to starting SIP conversations, can cause the maximum to be exceeded.

Information Value
Data type Integer
Default 120000 (recommended)
Range 1 <= n <= java.lang.Integer.MAX_VALUE


Maximum messages per averaging period

Maximum amount of SIP messages processed per averaging period. The averaging period is the period of time during which the average number of messages received by the container is calculated.

This average is used to determine the load for the container and to determine if the number of messages is approaching the maximum. When the maximum is exceeded, the stand-alone server or the proxy server continues to handle all in-dialog messages. Other non-dialog requests are rejected. When a container is in an overloaded state, the proxy server returns a 503 error.

Information Value
Data type Integer
Default 5000 (recommended)
Range 1 <= n <= java.lang.Integer.MAX_VALUE


Maximum dispatch queue size

Size of the internal dispatch queue. When the maximum queue size threshold is reached, the container queue becomes overloaded and begins to drop requests for new sessions. In this case, the container does not report its overloaded state to the proxy server.

Configure the system to limit the queue size to prevent the queue from reaching this threshold. If the internal queue reaches the overloaded state, incoming UDP packets are dropped until the queue is no longer in an overloaded state. Limiting the queue size enables better recovery if the CPU is used by other processes or threads and prevents the container from reaching out-of-memory conditions. When the value is set to 0, the queue size is unlimited.

Information Value
Data type Integer
Default 3200 (recommended)
Range 0 <= n <= java.lang.Integer.MAX_VALUE


Maximum response time

Maximum response time, in milliseconds, for an application. When the amount of time is exceeded, the container notifies the clustering framework that it is unavailable. We can disable this feature in the console by deselecting the check box and specifying a value of 0.

Use the maximum SIP response time setting cautiously because the calculated response time does not match the behavior of all applications. For requests, such as INVITE requests, where the responses are generated as a result of a user interaction, the calculated response time is extensive. However, the extensive response time is not caused by a delay in the SIP container. Therefore, you should not calculate the response time as a load factor. The recommended applications for effective calculation of response time are applications that respond immediately without a user interaction. The subscribe and register applications are relevant examples.

Information Value
Data type Integer
Default 0
Range 1 <= n <= java.lang.Integer.MAX_VALUE


Averaging period in milliseconds

Amount of time, in milliseconds, to use for calculating the maximum messages per averaging period. This setting is the sliding window during which the SIP container counts the number of messages sent to the container.

Information Value
Data type Integer
Default 1000 (recommended)
Range 1000 <= n <= java.lang.Integer.MAX_VALUE


Statistic update rate

Specifies control over the interval for which the container calculates averages and publishes statistics to Performance Monitoring Infrastructure.

Information Value
Data type Integer
Default 10000 (recommended)
Range 1000 <= n <= java.lang.Integer.MAX_VALUE


Locating SIP servers using DNS

Whether to enable locating SIP servers using DNS (Directory Name Service).

A SIP Uniform Resource Identifier (URI) can be resolved through DNS into the Internet Protocol (IP) address, port, and transport protocol of the next hop.

The value for the Primary DNS server name or Secondary DNS server name fields is a string containing one address and port tuple. The following examples specify an address and port tuple.

The container contacts the primary DNS server first; however, if the primary DNS server is unavailable, then the container contacts the secondary DNS server. If the secondary DNS server remains responsive, the container does not attempt to contact the primary DNS server.

Information Value
Data type Boolean
Default False

Primary DNS server name

Specifies an IP address and port tuple for the primary DNS server. If this server is not available, then the container sends a response to the secondary DNS server.

Information Value
Data type String
Default empty string.

Secondary DNS server name

Specifies an IP address and port tuple for the secondary DNS server.

Information Value
Data type String
Default empty string.


Thread pool

Thread pool to use for the SIP container.

If we do not choose a thread pool, the SIP container creates a new thread pool with maximum size of 15.


Related tasks

  • Configure the hang detection policy


    Related information:

  • Server collection