Why are Calls Failing?

Troubleshooting Failed Calls in WizCaller: Causes and Solutions

When making calls through WizCaller using your Twilio numbers, it can be frustrating to encounter issues where some calls go through while others do not. This article will walk you through the possible causes of this issue, how to identify the root cause using Twilio’s tools, and offer potential solutions to resolve it.

Understanding Why Some Calls Fail

If you notice that certain calls fail while others connect successfully, the problem is likely not with WizCaller itself, but rather with Twilio or external telecom providers. WizCaller serves as the platform through which calls are placed, but Twilio handles the actual connection to the recipient. When Twilio cannot complete a call, it is often due to restrictions imposed by telecom companies on certain numbers.

Here are the most common reasons why calls might fail:

1. Twilio Number Flagged as Spam
   One of the most frequent causes of failed calls is that your Twilio number may have been flagged by telecom companies as spam. Telecom providers can block calls from numbers they suspect are being used for spam or fraud. Even though Twilio provides a grace period before recycling numbers previously used by other customers, the flagging from telecom companies can persist for a longer period.
   • Why does this happen?
     If a previous owner of your Twilio number used it for aggressive or suspicious activity, it could have been marked as spam. Telecom companies might continue to block calls from that number, even after Twilio has reassigned it to you.
2. Telecom-Specific Restrictions
   Sometimes, a specific telecom provider may block calls from certain numbers, especially if they have flagged those numbers for spam-like behavior. This could explain why some calls connect while others do not, even if the numbers you’re calling are valid.
3. Twilio Geo Permissions
   If you’re trying to call numbers outside of your allowed geography in Twilio’s settings, calls may not go through. Twilio’s Geo Permissions settings control which countries or regions you can call. If your target number is in a country or region not permitted in your Twilio settings, the call will be blocked.

How to Identify the Problem Using Twilio Logs

To pinpoint the exact cause of failed calls, you should review Twilio’s call logs. Twilio provides detailed logs for each call, including those that fail, which often contain specific error codes that explain why the call didn’t connect.

Steps to Check Twilio Logs:

1. Check Twilio Error Logs
   Twilio’s error logs provide a detailed view of any issues that have caused calls to fail. You can access this by visiting Twilio Error Logs.
   Look for entries related to the failed calls and click on them to view more details about the errors.
2. Review Twilio Call Logs
   You can also check Twilio’s call logs for a more general overview of all calls made, including successful ones and those that failed. Visit the Twilio Call Logs and search for the specific calls that didn’t connect. Click on the log entries to see detailed reasons for the failure.
   • Common Error Messages:
     Some common error messages you might encounter include:
     • SIP 603 Decline: This often means the call was rejected by the recipient’s carrier.
     • SIP 604 Does Not Exist Anywhere: This suggests the number you’re calling is not recognized by the carrier.
     • SIP 484 Address Incomplete: This indicates there may be an issue with how the number is formatted.

Solutions to Common Call Failure Problems

Once you’ve identified the cause of the issue using the Twilio logs, you can apply the following solutions:

1. Replace the Twilio Number
   If your Twilio number has been flagged as spam, the quickest solution is to purchase a new Twilio number. Once you have a new number, test it by placing calls to the numbers that previously failed. This solution has worked well for other WizCaller users in the past.
   • Test Different Numbers: If you already have more than one Twilio number, try placing the failed calls using a different Twilio number to see if the problem persists.
2. Verify Geo Permissions
   Ensure that your Twilio account has the necessary Geo Permissions enabled for the country or region you’re calling. You can update these permissions in your Twilio account settings to include the regions you need to reach.
   • Visit Twilio’s Geo Permissions for Calls to review or update the allowed regions.
3. Contact Twilio Support
   If you’re unable to resolve the issue with the above steps, it may be worth reaching out to Twilio support for further assistance. Twilio can provide more in-depth analysis and help lift any blocks or restrictions on your numbers.

Additional Troubleshooting and Support

If you find that troubleshooting through Twilio logs seems too complex, or you want personalized help, reach out to our support team at support@wizcaller.com. In your email, you can send us screenshots of your Twilio logs; this can help quickly identify the problem and get you back to making calls.

For detailed steps on making calls in WizCaller, check out this guide on making calls with Twilio numbers.