Switchvox Server Is Not Replying to SIP Invites

Owned by Merry Arpaia
Oct 22, 2024
2 min read

  1. First, check for a blocked IP Address under Server > Access Control Rules > Blocked IP Addresses (or Server > Blocked IPs). Verify that the Provider's IP address is not blocked.

  • If it is, unblock all instances of the blocked IP address, then add an Access Control Rule for that IP address, and enable SIP and Never Block IPs in the rule (under Server > Access Control > Create Access Control Rule).

  1. Next, Verify the firewall configuration: disable SIP ALG or any other SIP features. See Firewall Checklist for more information.

  2. Check for Alerts under Server > Server Information to view any current Alerts on Memory, Disk or Load, as this can cause the server to behave erratically and stop replying to SIP Invites. You can also go to Tools > Alerts Manager > Alerts Log > Retrieve Alerts to view past dates for any Alerts.  If anything is over threshold investigate the cause of the Alert. For example, are the Concurrent Calls too high for this appliance? Are you running v.6.x on an older appliance (not recommended)? Check Server > Error Logs for any other problems.

  3. If the problem is intermittent, go to Setup > VOIP providers > Modify pencil > Connection Settings. Verify that Always Trust this Provider is set to Yes. If Qualify Hosts is enabled, try disabling this and see if the issue is resolved (not all Providers allow SIP Options packets).

  4. Run a packet capture while the issue occurring: Check the packet capture to determine if the Invites are using a hostname or if there are delayed responses to the Invite.

  • Sometimes DNS queries fail, for example:

PBX queries the DNS from googles DNS server will sometimes replies with:
373 2012-11-09 15:59:02.808782 8.8.8.8 10.10.10.8 DNS Standard query response, Server failure
The server will not reply to the Invites as it is unable to resolve the host name. Do you have a Google DNS server setup in the DNS entries on the Server > IP Configuration page?

NOTE: Making changes to this page will restart server processes and drop all active calls.

  • Check to see if any replies between the server and the Provider or phone are delayed. This can indicate packet loss or latency on the network or from the ISP (internet connection).

If the Switchvox server is still not responding to SIP invites after checking these steps, please contact Technical Support.

Unable to render {include} The included page could not be found.