What is SIP ALG? Should you disable it? That depends

Here’s a scenario you’re likely familiar with. You just installed a VoIP system and are eager to begin reaping the benefits. There’s just one problem…

…it’s not working correctly.

Perhaps you’re experiencing a lot of dropped calls for reasons you can’t explain. Maybe you keep dealing with a cluster of ringing and calling at the same time. It’s more than possible this is the result of your SIP ALG feature. 

Let’s take a look at what SIP ALG is and why it’s sometimes (but not always) a good idea to disable it.

Defining the SIP ALG Feature in Your VoIP System

Here’s a quick refresher to get you started. Your VoIP system is short for ‘voice over internet protocol’, relying on a broadband connection to connect calls or leave voicemail messages.

SIP ALG is an acronym referring to certain features used in your VoIP system to provide you with flexible, reliable call services. It’s actually found in a variety of networked routers and is used to manage incoming information. Think of it as a firewall, but for your phone service.

SIP (Session Initiation Protocol)

Consider the SIP the backbone of your VoIP apps and devices. It’s responsible for registering all your devices and linking them together. 

Any time your VoIP session works properly, you can thank SIP for it. Sadly, SIP can still go a little too far and interfere with your calls if it’s not regulated. Generally, Session Initiation Protocol is used to handle elements such as:

  • Regulating call audio
  • Maintaining call presence
  • Managing voicemail

ALG (Application Layer Gateway)

Now for the other side of the coin. The Application Layer Gateway is used to improve connectivity between your devices, sorting out data packets so they’re not lost in the shuffle.

Do you often experience dropped calls out of nowhere? Are you sometimes left with one-way audio that doesn’t resolve itself? You could be experiencing an ALG that isn’t compatible with your VoIP package.

Most Common Signs You Have an Incompatible SIP ALG

If you regularly use a home computer or laptop, you’ve probably had incidents where your firewall interfered with essential functions. This is a common hiccup in today’s technology and a sign you need to reassess a few things.

You know your VoIP is struggling with SIP ALG interference if you experience the following:

  • Randomly dropped calls
  • A lack of ringing when you call someone
  • Constant one-way audio

How Can You Fix Your SIP ALG Connection?

Just like your computer’s firewall, your SIP ALG is getting in the way of your phone system and your VoIP service provider. While this can sound like a complex fix, the fact of the matter is quite different.

All you have to do is pull up your router’s firmware, visit the ALG page, and uncheck your SIP ALG box. You may need to gain access with your admin password if you have security settings in place.

What are Today’s Most Popular Routers?

There are several popular router brands today that use SIP ALG to manage VoIP systems. While they all have slightly different menu options, their basic function is the same: providing you with a smooth call experience.

Common router brands you can try include (but aren’t limited to):

  • Actiontrec
  • Adtran
  • AT&T
  • Cisco
  • Netgear
  • Sonicwall
  • Verizon

Keep in mind that it’s not enough to just disable your SIP ALG. You also need to reboot your entire system for the changes to take effect.

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What are the Benefits of Disabling SIP ALG?

You may be wondering as to the benefits of disabling SIP ALG. If it functions similarly to a firewall, does that mean your calls will have their security compromised?

Fortunately, the majority of businesses don’t experience any trouble when they disable their SIP ALG feature. If anything, they gain the ability to enjoy a better call experience now that their data packets are no longer filtered. You’ll also enjoy benefits such as:

  • Fewer call interruptions
  • Improved functionality with desk phones
  • Clearer audio
  • No missed voicemails
  • No missed calls

The only time you should keep your SIP ALG feature on is if you’re explicitly instructed by your VoIP provider.

Simple Tips to Improve Your VoIP Experience

Think you could improve your VoIP experience a little more? Here are a few tips to ensure you’re getting the most out of your phone systems.

1. Choose High-Speed Ethernet

Running a firm means always looking for ways to save on green. High-speed Ethernet is not an area you want to cut corners on, as it will drastically reduce signal loss. 

Jittery audio quality and frozen video screens are just a few side-effects of slow Ethernet.

2. Improve Your Firmware

You can never be too careful with your business operations. Always double-check with your provider to see if they have any new patches or updates to your security system.

These updates are usually free and provided on a rolling basis to keep you satisfied with your product.

3. Enhance Security with VLAN Tagging

Worried about security issues when disabling your SIP LAG feature? You’re not alone: 72% of respondents to a survey on data privacy are worried about identity theft and fraud. Consider Virtual LAN (or VLAN) Tagging.

This useful feature will prioritize your VoIP data over all else, reducing unnecessary traffic and keeping you safe from security threats.


Should you disable your SIP LAG feature? Most of the time: yes. 

While the SIP LAG feature is designed for security, it sadly interferes with many basic business functions. Your SIP LAG should be disabled if you are experiencing dropped calls, missed voicemails, and diluted audio. This is easily done by pulling up your router’s Settings or Admin page to disable your SIP LAG feature.

Only keep your SIP LAG feature on if your VoIP provider specifically asks you to. Otherwise, you’re better off updating your firmware or using VLAN Tagging to keep your data safe.

Give your business the ability to stay connected at all times. Contact us today to receive a competitive quote on today’s most efficient phone systems and cloud resources.

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