Error '408 Request Timeout' indicates that the client is not receiving any response from the server that you are trying to connect to. This error is likely caused by incorrect server information (domain, server address) entered in your SIP account.

OR  

There is no Wi-Fi or cellular connection. You will know you do not have a Wi-Fi connection if you do not see the icon at the top of the iPhone. Go to the iPhone settings (Setttings > Wi-Fi). For cellular connection problems, deal with them in the usual way.

Further troubleshooting:

  • Make sure your Wi-Fi connection is strong and stable. Double-check your connection by opening Safari and browsing to a web site.
  • Make sure you entered the domain correctly. Make sure there are no spaces at the end.
  • If you know how to do so, try disabling your firewall to see if this allows registration.
  • If you've verified all of the above information and still get the 408 error message, please try the following troubleshooting steps (note you'll have to disable the account to change the settings, then re-enable):
    • Under Accounts --> Your Account --> Account Advanced, please try to change Global IP Wi-Fi to Off and see if it resolves the issue
    • If the above suggestion doesn't work for you, please try;
      • Changing the Network Traversal Strategy under the Advanced Settings
  • Try to use Server Managed

 OR

  • Try Application Managed

 OR

  • Try to set to Custom Configuration and set DNS SRV to OFF and STUN Wi-Fi to ON; set to Custom Configuration and set DNS SRV to Off and STUN WiFi to OFF.


Please make sure you apply the settings and run a test after every change.

If testing does not solve the issue with Global IP Wi-Fi OFF, repeat the steps with Global IP Wi-Fi ON.
Set Topology -> None if experiencing connection issues with main account or with presence info (i.e. parking lots)