How Much Bandwidth Do I Need for VoIP?

Bandwidth is one of the most important considerations when deciding if VoIP is right for your business. Unlike traditional phone systems with use the PSTN (Public Switched Telephone Network) to send and receive phone calls, VoIP based calling depends on your data connection, typically a broadband circuit (Cable modem, DSL, Fiber (FiOS), T1, Metro Ethernet). The amount of bandwidth consumption per VoIP call depends on what codec you are using.

It’s also important to note that just because you have thirty people in your office does not mean you need enough bandwidth to make (30) concurrent VoIP calls. When was the last time everyone in your office was on the phone at the same time? Unless you are running a call center with agents constantly on the phone, chances are you’ll need to provision bandwidth for perhaps 10-15 concurrent calls if you have an office of 30.

The table below compares several popular VoIP codecs, and gives you a ballpark estimate of the amount of bandwidth a single VoIP call will consume on your data/internet connection. For the purposes of this post I factored in all the various overhead and rounded it a bit.

Data connections these days are typically offered in Megabytes, and you also need to factor in the amount of bandwidth you’ll need for everyday office activities such as web browsing, email, file transfers, uploading, downloading, etc. Before you choose a vendor to deliver an internet connection to your office, be sure to mention that you intend to use VoIP, and make sure they offer sufficient bandwidth on the connection they are offering you to support both Voice and Data.

Also be sure to check with your vendor or manufacturer to see which VoIP codecs are supported in the products you are purchasing. G.729 and G.711 are probably the 2 most popular codec choices, and are almost universally supported in today’s SIP compliant VoIP phones and VoIP phone systems.