• Verify Airplane Mode and Do Not Disturb are both disabled on device
• Check bars of service on the device. Phone must have data signal (4G, 4G LTE, 5G, etc.). If phone shows two bars of service or less, it may be a coverage issue.
• Power cycle device and re-test (turn completely OFF, and then power back on)
• Power cycle device outside and test service. Interference indoors may be affecting service
• Reset the network settings on the device
  • iPhone: Settings -> General -> Transfer or Reset iPhone -> Reset -> Reset Network Settings
  • Android: Settings -> General Management -> Reset -> Reset Network Settings
• Verify VoLTE calls are enabled (option may not be available on all devices
  • iPhone: Settings > Cellular > Cellular Data Options and turn on VoLTE or Enable LTE
  • Android: Settings -> Connections -> Mobile Networks -> Toggle on VoLTE calls
• Check software version and ensure phone software is up to date. Power cycle device and re-test once complete
• Test the service in another device by inserting sim card into a different phone
  • If the call works in the different phone, the issue lies with the original device
  • if the call does not work in the different phone, the issue lies with the cell service