Seeing SIP 480 “Temporarily Unavailable”? Here’s What To Do

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Getting stopped by SIP 480 “Temporarily Unavailable” error messages can be one of the most frustrating parts of making outbound VoIP calls.

Basically, these error codes mean that the number you’re trying to call isn’t reachable for some reason. Most VoIP users encounter it when trying to call an unregistered number, when the call is rejected by the provider, or when the end device is not in service.

Fortunately, there are a lot of common fixes for SIP 480 errors, and by taking a closer look at how SIP works, we can understand why many of the SIP errors occur in the first place.

Graphic to illustrate how SIP-based telephony works.

SIP 480: What’s Really Going On

SIP technology makes VoIP possible by starting and ending the transfer of information between two communication devices. It works by connecting devices over the internet to share live audio, instant messaging, video, files, and other forms of multimedia.

At the core of SIP technology lies request and response codes, which flow between parties to enable communication. Request codes are sent via a server to establish a form of communication between at least two users, while response codes are sent back to say if a request was successful or not.

Again, the 480 “Temporarily Unavailable” response code is a type of error code that indicates a client response failure, meaning the number being called isn’t available or responding. This often happens for one of the following reasons:

  • The recipient is offline
  • An account hit its limit
  • The call was rejected by the provider or end device
  • The device being called is unreachable or unregistered
  • The service has reached its maximum capacity

Common Fixes for SIP 480 Response

Just about all of the issues that cause 480 error responses have practical solutions that you can implement on your end without too much trouble—though contacting your provider may be necessary in some cases.

The recipient is offline

One of the most common reasons for a SIP 480 “Temporarily Unavailable” error is when the call recipient is offline.

When this occurs, the recipient’s internet, landline, or other communication provider isn’t working temporarily. You can confirm this by trying to contact the call recipient with another form of communication, such as email or a traditional phone call, and check the status of their connection.

If you can’t or don’t want to reach the recipient any other way, you can also contact your provider to check their status and confirm if they’re offline. Once you confirm their connection has been reestablished, you can call them again with your VoIP phone.

An account has hit its limit

Another common reason for SIP 480 errors is when an account has reached a limit, such as the maximum number of calls allowed in a certain time period.

To find out, check your settings carefully and see if there’s any limits placed on the number of calls you can make. Contact your provider if you’re unable to find this information yourself and can’t personally make any changes to the number of calls allowed on your end.

Slowing down your calling can also help if there’s a limit on the number of calls you can make in a short amount of time. If the limit was reached, you may just have to wait it out.

The call has been rejected by the provider or end device

Sometimes your call may be rejected by the provider or the device on the other end for reasons outside of your control. This can be frustrating, but contacting your provider to learn more is usually your best bet in understanding why this occurred and the fixes for it. Otherwise you can try to call again later on.

The device being called is unreachable or unregistered

An unregistered device or provider can also trigger a SIP 480 response code.

If you suspect this is the case, contact your call recipient using other means to see if their device and provider are successfully registered or not. You can also contact your own provider to get more information and check on the recipient’s device registration status.

The service has reached its maximum capacity

If your service has reached its maximum capacity, a SIP 480 error code could result.

Contact your provider to see if this is the case and if there’s any way your capacity could be increased. If not, adjust your calling frequency and schedule with your service capacity in mind.

If all of these options fail, you’ll need to do further troubleshooting to figure out why you’re still getting the SIP 480 response. Calling the number with another VoIP number if you have it can work, as can calling with a traditional phone.

SIP 480 vs. Other Request Failures

In addition to the SIP 480 error code, a number of other error codes exist that indicate request failures. Having a better grasp of these can help you understand how SIP technology works and how to troubleshoot it.

  • 403 Forbidden: The request was understood, but the server still refused to do it.
  • 407 Proxy Authentication Required: Authentication with a proxy is required.
  • 408 Request Timeout: The server wasn’t able to find the user in a suitable amount of time, though the request can still be repeated.
  • 413 Request Entity Too Large: The body of the request is too large to process.
  • 415 Unsupported Media Type: The body of the request is in an unsupported media format.
  • 420 Bad Extension: The SIP Protocol Extension wasn’t understood by the server.
  • 424 Bad Location Information: The request’s location wasn’t correct.

Solve SIP 480 Errors

SIP 480 errors when trying to make VoIP calls are certainly annoying, but having knowledge of what they are, why they happen, and how to fix them can help troubleshoot them better in the future. If you run out of pragmatic solutions, remember that you can always call your provider for more help.

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