IP Destinations Connectivity Feature

The device can be configured to check the integrity of the connectivity to IP destinations of Tel-to-IP routing rules in the Tel-to-IP Routing table. The IP Connectivity feature can be used for the Alternative Routing feature, whereby the device attempts to re-route calls from unavailable Tel-to-IP routing destinations to available ones (see Alternative Routing Based on IP Connectivity).

The device supports the following methods for checking the connectivity of IP destinations:

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Network Connectivity: The device checks the network connectivity of the IP destination configured by the 'Alt Routing Tel to IP Connectivity Method' parameter:

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SIP OPTIONS: The device sends "keep-alive" SIP OPTIONS messages to the IP destination. If the device receives a SIP 200 OK in response, it considers the destination as available. If the destination doesn't respond to the OPTIONS message, then it is considered unavailable. You can configure the time interval for sending these OPTIONS messages, using the 'Alt Routing Tel to IP Keep Alive Time' parameter.

These parameters are configured in the Routing Settings page (Setup menu > Signaling & Media tab > Gateway folder > Routing > Routing Settings), as shown below:

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Quality of Service (QoS): You can enable the device to check the QoS of IP destinations. The device measures the QoS according to RTCP statistics of previously established calls with the IP destination. The RTCP includes packet delay (in milliseconds) and packet loss (in percentage). If these measured statistics exceed a user-defined threshold, the destination is considered unavailable. Note that if call statistics is not received within two minutes, the QoS data is reset. These thresholds are configured using the following parameters:

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'Max Allowed Packet Loss for Alt Routing' (IPConnQoSMaxAllowedPL): defines the threshold value for packet loss after which the IP destination is considered unavailable.

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'Max Allowed Delay for Alt Routing' (IPConnQoSMaxAllowedDelay): defines the threshold value for packet delay after which the IP destination is considered unavailable

These parameters are configured in the Routing Settings page (Setup menu > Signaling & Media tab > Gateway folder > Routing > Routing Settings), as shown below:

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DNS Resolution: When a host name (FQDN) is used (instead of an IP address) for the IP destination, it is resolved into an IP address by a DNS server. The device checks network connectivity and QoS of the resolved IP address. If the DNS host name is unresolved, the device considers the connectivity of the IP destination as unavailable.

You can view the connectivity status of IP destinations in the following Web interface pages:

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Tel-to-IP Routing table: The connectivity status of the IP destination per routing rule is displayed in the 'Status' column. For more information, see Configuring Tel-to-IP Routing Rules.

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IP Connectivity: This page displays a more informative connectivity status of the IP destinations used in Tel-to-IP routing rules in the Tel-to-IP Routing table. For viewing this page, see Viewing IP Connectivity.