There are many reasons for the growing popularity of SIP trunking for business and wanting to use a cloud phone system. The potential for substantial cost savings tops the list for most buyers.
With a relatively low initial investment and a few simple set up activities, most businesses can quickly and easily make the cost cutting move to SIP with little to no disruption.
As simple as it can be, there are a few steps you should take before you make the switch and things to consider and understand.
1. Check if your equipment will be problematic because of SIP ALG.
What is SIP ALG?
SIP ALG stands for Application Layer Gateway, and is common in many commercial routers. It was developed to prevent some of the problems caused by router firewalls by inspecting VoIP traffic (packets) and if necessary, modify it. Think of it as a VoIP packet helper to go between your NAT (internal network) and the public internet.
How can it affect VoIP?
Even though SIP ALG is intended to assist users who have phones on private IP addresses, in many cases it is implemented poorly and actually causes more problems than it solves. Most, if not all providers often find that the SIP ALG modifies SIP packets in unexpected ways, corrupting them and making them unreadable.
This can give you unexpected behavior, such as phones not registering and incoming calls failing, and for most people 1-way audio. Therefore if you are experiencing problems we recommend that you check your router settings and turn SIP ALG off if it is enabled.
How do I turn off SIP ALG?
The method to disable SIP ALG will depend on your router and modem/router provider. In the first instance, we recommend checking the manufacturer’s handbook that came with your device. Alternatively check the internet and support forums for advice (type your router make and model into a search engine, along with “disable SIP ALG”).
Please note that if you are using a home internet modem, your provider may not allow for you to disable SIP ALG. For business modems, you should be able to turn it off. Either case, please check with you provider/manufacturer.
SIP VoIP Client Based Testing
This link will download a small program that can test for the presence of a SIP ALG on the network the host PC is connected to. After downloading, open the file and accept any permissions your windows machine may ask for.
If the results = False then a SIP ALG was not detected by the client.
If the results = True then a SIP ALG is active and should be turned off.
SIP VoIP Web Based Testing
Visualware is a provider of internet based VoIP testing tools.
Click on the link to test your VoIP efficiency.
The web test will simulate 1 VoIP Call using the 711 codec and provide a real-time analysis of that call. After the test completes click on the ‘Summary’ tab and look at the bottom. Should read SIP is not detected or is detected.
Or on the ‘VoIP’ tab, in the bottom right, white result box, look for ‘SIP ALG Firewall’. It will indicated Y or N.
If you see “SIP ALG Firewall: Y” then a SIP ALG is active and should (more often than not must) be turned off.
If you see “SIP ALG Firewall: N” then a SIP ALG is was not detected. Nothing to do.
Disclaimer: The analysis represents ONLY the quality of the the single session/call and should not be used as a benchmark for real calling scenarios with multiple active calls during an extended period of time.
2. Perform a Test
Several factors are relevant to your calling experience with SIP. Your hardware, internet connection, router, and SIP trunking provider all play a role. The best way to ensure that you get the quality you need is to test the solution in your environment. Contact us for an assessment and we can do a proof of concept with you.