What is VoIP Codec?

By Jelani Harper
Updated: September 19, 2011

What is VoIP Codec?

VoIP codecs are algorithms that perform the essential functions of VoIP—converting voice data into digital signals that are reconverted into voice data again at their destination to allow for telephone conversations. Codec is a hybrid of the words “coder” and “decoder”; these algorithms perform other functions endemic to the transporting of digital data including compression and packet switching. There is a wide variety of codecs that VoIP telephony utilizes, some of which are more commonly used than others.

Conversion Process

Codecs perform the process of converting audio data into digital data by sampling the initial audio signal at rates of several thousand times per second. Each sample is then converted into digital data, which is compressed before traveling through bandwidth to the receiver on the other end. The reassembly of the digital data into audio includes minute particles that are missing due to the conversion process, but which are typically too small for users (who only hear continuous audio) to detect. The conversion process is called encoding; the process by which digital signals are reconfigured into audio is known as decoding.

Compression

Compression is a key function performed by VoIP codecs, and is the name of the process whereby the size of audio data is decreased so it can travel in smaller increments over bandwidth to the other user. Bandwidth is typically expensive and a valuable commodity; compressing data makes it lighter and easier to transport and helps to maximize the performance of the bandwidth and the quality of the data it is both sending and receiving. Compression can be somewhat of a tricky process, however, because the more tightly data is compressed the less optimal its sound quality is. Conversely, the less tightly the data is compressed the better it sounds—and the more strain it places on bandwidth, which may require greater amounts to transport the data. As a result, codecs vary considerably in required bandwidth, sound quality, forms of compression and computational requirements.

Common Codecs

One of the most widely used codecs in current VoIP technology is known as G.729A, which has a sampling rate of 8,000 times per second. Another highly prevalent codec is CS-ACELP, which is useful for streamlining and organizing bandwidth, and which also contain a component known as Annex B. Annex B is the part of CS-ACELP that is largely responsible for packet switching, which means that if no one is talking data will not be transmitted throughout VoIP. Packet switching is widely considered superior to its alternative, circuit switching.
 

Featured Research
  • The Best 2018 Phone System Upgrades for Your Business

    Whether 2017 has been a huge success or more of a disappointment for your business, it’s time to start looking for ways to improve in 2018. With customer service and communication becoming an increasingly important component of success for all businesses, your phone system is a great place to focus. Even small upgrades here can pay big dividends. more

  • 8 Ways to Get More From Your VoIP System

    Many businesses adopt VoIP to take advantage of the cost savings without spending enough time reviewing the features and benefits made available by different solutions. If this is true for your business, there’s a good chance you could be getting more from your VoIP system in the form of even lower costs or improved employee productivity. You may even find that your current software offers features that you aren’t taking advantage of! more

  • 7 Ways the Wrong Phone System Can Haunt Your Business

    The wrong phone system could be haunting your business - and we’re talking about problems more serious than ghosts and ghouls. From increased costs to issues with scaling, we’ve identified seven important ways that a less than ideal phone system could be holding you back. You’ll be surprised at how much of a difference this can make to your bottom line too. more

  • Ditch Your Fax Servers

    An in-house fax server gives an IT department centralized management and monitoring over the entire enterprise's faxing. This can help your company track usage and better maintain records for auditing and record keeping. However, there are serious drawbacks that come with utilizing an in-house fax server solution and these range from security to cost-prohibitive pricing. more

  • The IT Manager's Survival Guide

    As an IT manager, maintaining physical fax servers and infrastructure is not a high priority. However, fax capability remains a business need simply because chances are your industry is dependent on its security. What if there was a way to reduce the amount of time spent handling fax complaints and maintaining physical servers? And this way took into account security, cost savings, and freed up your IT resources. Would you be interested? more