Are you getting a VoIP Unknown URI Scheme error code? When you use a VoIP phone like a Yealink SIP-T41P or a T42G IP phone, you might need to troubleshoot error codes. For example, "VoIP Unknown URI Scheme" might come up as a code. But, with advanced SIP technology, you can look up any error codes and know what causes it.

Here is a little insight into the VoIP unknown URI scheme error code so you can understand what it means and how to fix it.

SIP Technology

Before getting into SIP URI scheme error codes with VoIP phones, it's important to understand SIP technology. SIP stands for session initiation protocol. It's an advanced technology which uses VoIP phone communications.

SIP technology lets people communicate globally with voice over internet protocol (VoIP) technology. When SIP technology is used, it can help a business reduce costs because most calls are free. There are no hidden surcharges either. It's one of the reasons that 15.3 percent of businesses have switched to VoIP every year through 2017.

Businesses that use PBX for internal and external communications may use SIP protocols. An advantage with SIP technology is when you use a SIP app, it's free. Let's take a brief look at how SIP works to help you understand the error codes you might receive.

How SIP Works

With SIP technology, you can set up SIP addresses on your VoIP phone. You can also use your SIP credentials to help you configure your SIP client. To communicate through SIP you will need:

  • Your SIP address and account details: The SIP address is free with several providers.
  • Your SIP client: This is the program that you will install on your mobile device or your work computer. It's free with your VoIP service.
  • Your connection to the Internet: You will also require sufficient bandwidth to support your connection.
  • Your headset or phone: You can also use an earpiece or webcam.
  • A connection on the other end: This may be another colleague with a SIP address.

What Is VoIP Unknown URI Scheme?

The error, "416 Unsupported URI Scheme" or "VoIP Unknown URI Scheme", is a common one. It can occur when using a VoIP phone with SIP technology. With this code, the phone extension isn't working or isn't supported by the Uniform Resource Identifier (URI).

416 is an error that comes up when a call doesn't go through. It's similar to an IP address that isn't correct and gives a code "404 not found". When you see the SIP URI scheme message, it's letting you know that the address isn't configured correctly. This means you have a SIP URI that's not valid. To sum it up, the URI is unknown to the server. Here's an example.

In your VoIP phone, let's say you're dialing an extension. You might dial But, the address is already included. So, what you're actually dialing is You were likely using the full URI. Hence, you'll receive the 416 error code. That's one way to try to troubleshoot the error message.

Another way to troubleshoot the error message is to try the following steps:

  • From the web interface on your VoIP phone go to Settings and Configuration.
  • Then go to Export CFG Configuration File.
  • When you edit the CFG File, add the following two lines: custom.features.redial_via_local_sip_server.enable = 1 features.redial_via_local_sip_server.enable=1
  • Next, go back to your web interface of the VoIP phone and upload your CFG configuration file.
  • You may see that your old history entries still show the error code and that they failed, but any new ones will now work. If you need it, here's a helpful list of error codes and their meanings.

8x8 Is Here to Help with Your VoIP Setup

If you need help with your VoIP setup, 8x8 can help. 8x8 provides effective communications solutions to help with your new VoIP setup. With ultra-fast VoIP and cloud deployment, you can integrate your phone system with all your applications. That way you can spend more time in front of clients and customers and less time troubleshooting error messages.

VoIP phones that feature SIP technology offer your business the latest communications technology. Because most video and voice calls are free, you can meet your bottom line and scale your business. Addressing error messages is simple and if you need to troubleshoot your VoIP phone service, 8x8 is here to help.

Choosing the right technology is crucial to a growing business. Take the uncertainty out of the equation by choosing a SIP technology provider that can scale to meet your business' needs whatever they may be at any given time. Call 1-866-879-8647 or fill out an online form to request a no-obligation quote from an 8x8 product specialist.


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