VoIP Call Recording

A codec – a device or computer program capable of encoding or decoding a digital data stream or signal – is essential in the technological market. For companies like SIP-based VoIP call recording provider, SIP Print (News - Alert) codecs are used to encode the audio of the conversation into IP packets. 



According to Jonathan Fuld, chief technology officer at SIP Print, the company captures these packets and uses the codecs to reverse the packets into audio and then store it as a wave file. 

With two different types of codecs SIP Print focuses on – namely g729 and g711 – users benefit from a reduced cost from a traditional circuit switch telephone technology, or a time-division multiplexing system. 

“Everything gets simplified by using a codec to compress the audio into IP Packets,” Fuld said. 

While the g711 codec is primarily used in telephony, and can also be used in a fax communication over IP network, or “FoIP,” method, the g729 differs slightly. The g729 is an auto data compression algorithm that compresses digital voice in packets and is used mostly in VoIP where bandwidth must be conserved, since it has low bandwidth requirements. 

Both codec options, however, have multiple extensions that also play a role in the development of SIP Print’s systems. 

The g711 codec has a g711.1 extension, published as a ITU-I recommendation, while the g729 has been extended to g729a and g729b which are equipped with DTMF tones, fax transmissions and high-quality audio cannot be transported reliability with this codec, as the DTMF requires the use of the RTP payload for DTMF digits, telephony tones and telephony signals, Fuld said. 

“G711 offers high quality encoding, and uses more bandwidth and a low cpu cycle,” Fuld said. “G729 offers low quality encoding, with better compression, less bandwidth usage and has higher cpu cycle requirements.”

While there are many differences between the g711 and g729 codecs, there’s one specific characteristic that sets them apart: g711 is free and g729 is not. 

So, why would a user pay for a codec when there are free codecs offered?

“In the case of SIP Trunking, the provider and the PBX (News - Alert) vendor pay for the g729 codec to reduce bandwidth usage,” Fuld said, adding that there’s no reason to utilize a paid codec, if an internal lan is running VoIP. 

And, since there’s no advantage on a lan under gigabit speeds, it makes financial and economical sense to utilize the free g711 rather that coughing up the fees for the g729, despite its low bandwidth standards.