What is the Bandwidth Needed For VoIP?

Bandwidth for a layman translates to the speed of the Internet connection but there is a broader definition as well as use of the term. Technically, bandwidth is the frequency range through which data transmission takes place. Bandwidth is not only restricted to the Internet and is used for all kinds of radio and wireless transmission. If we are talking about large bandwidth then it implies that at any point in time, a large amount of data can be transmitted. Once again I reiterate – Bandwidth does not mean Internet speed but you can use that meaning for your convenience.

How to measure bandwidth?

Hertz, Kilohertz, and Megahertz are the units used for measuring bandwidth.  When someone says 1 MegaHertz then they essentially mean one million Hertz.

This is different from an Internet connection speed which is is measured in Kbps (Kilo bits per second) or Mbps that refers to 1 million bits per second. This is a measurement of the number of bits transmitted in a second. Data Transmission speed is the correct way of describing Internet transmission speed. You will be able to decide whether your connection speed is good or not. This in turn will give you an idea whether it is feasible to use VoIP with the existing connection or upgrades are needed.

The Need to Check Your Connection Speeds

For all the organizations using Internet for both data and voice transmission, it becomes imperative to run a check on the bandwidth for ensuring good call quality. VoIP itself does not have any upfront fees but you will have to get the right bandwidth and this can be pretty costly. Bandwidth costs incurred by organizations are often high and if you are using the same Internet connection for data as well as voice then it is mandatory to use higher bandwidth. Voice signals are bulkier compared to the text signals and this is why it uses higher bandwidth during transmission. So when you have a connection with higher speed or higher bandwidth, you are going to experience better voice quality.

With the passage of time, bandwidth is getting less expensive, and now even the smaller companies can afford connections with higher bandwidth. Broadband in its latest avatar offers greater speed as compared to the old dial up connections.

Bandwidth Calculation

A normal voice call on VoIP has two components – an upstream and a downstream. In the upstream, your voice travels to the other party. In the downstream, the other party’s voice travels to you.

The lowest quality calls need roughly 15 kbps for each stream or a total of 30 kbps for each call. Mind you, I said each call. So if you have ten calls, you need 300 kbps. A good quality voice call would need 90 kbps for each call. So you now have a simple multiplication factor. Guess the number of simultaneous calls you have during peak times, and multiply that by 90.

There is small catch. This number you calculated is only for VoIP voice calls, and should be allocated for that task only. It cannot be mixed with your regular data usage.

If you are planning for video conferencing, each video call would need 1.2 mbps at a minimum.

Other Factors That Play

If you are calculating bandwidth then you should never assume that all the channels are used for every communication. For instance, when there is a normal conversation then there is a lot of silence, which implies that data packets are not at all sent during that period. Thus, full bandwidth is almost never used during VoIP calls. The usage of bandwidth depends on the datalink protocols and there are numerous factors that actually influence the bandwidth usage. Some of the factors that impact bandwidth are VPN headers, ATM cell headers, payload size, IAX2 Trunked and header compression.

You can use a bandwidth calculator like this to calculate your existing Internet connection speed.

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