How to troubleshoot outgoing and incoming VoIP call issues

VoIP, as any phone system, is prone to issues that might or might not be related to your provider’s network. To identify the possible causes of your VoIP issues, follow these simple steps that might spare you lengthy hours of troubleshooting your VoIP line / Hosted PBX extension, or significantly reduce the time engineers spend on identifying the possible causes of your VoIP issues.

What can you do if you cannot call out from an IP Phone?

  1. The first indication about how you could resolve the issue is the message you are getting when trying to call the number from your Hosted PBX system or VoIP phone line. It could be that the number is out of service or does not exist.
  2. Ensure that you are dialing the number correctly. Outside your Hosted PBX system, if you are trying to reach an international number, please ensure that the number is dialed in the following format: country code + number, or 011 + country code + number with some VoIP providers. Some countries have an initial 0 at the beginning of each number that is only added when calling locally, please ensure that you remove it before calling (example: the London UK number +44 0203-695-2503 will be dialed as +44 203-695-2503).
  3. Verify if there is an issue with calling only a certain number, or all numbers. Try to call other numbers; if it doesn’t work, there could be a general issue that needs to be investigated by your VoIP provider.
  4. Dial the number from a network outside your VoIP business phone system. If the number cannot be reached from other networks either, your destination number must be experiencing issues in receiving calls and the owner of the number will need to contact his/ her phone service provider to investigate the issue. If the number can be reached from another network, you will need to contact your VoIP provider in order to open a trouble ticket. In this situation, kindly ensure that you include the following information in your request: destination phone number, time of call(s), description of the issue (i.e. “dead air”, error message, one way voice, etc.), it will help track your call a lot faster.


7 things to verify if you cannot receive calls using a VoIP phone service

  1. Call your phone number from various phone providers. There is a possibility that only certain numbers are unable to call your number. If you notice a pattern and your number is not reachable from a certain provider, the owner of the number will need to contact his/ her phone service provider and open a ticket.
  2. Check the power indicator to verify if your IP phone is active.
  3. Ensure that the Do Not Disturb feature is turned off on your IP phone.
  4. If your number has been recently ported, verify the completion date with your VoIP provider.
  5. Ensure that the Call Forward feature is turned off on your IP phone and in your WebCare account if you have one.
  6. Verify if there is an error message on your phone screen, and refer your IP Phone’s manual error list.
  7. Internet connections have firewalls that may block receiving calls; ask your network administrator or Internet Service Provider to disable firewall or set port triggering.