Last Change: February 22, 2007
© 2008 Hampton Software Ltd

Codec Selector

The codec is the method by which voice is encoded for transmission over the network. Articulation supports two codecs, G.711 and GSM; G.711 provides better voice quality but uses up to 4 times more bandwidth than GSM. GSM is the codec used by many cell phone carries for cell phone calls.

In order to determine the best codec for your network you can use the table below. The codecs to use may be selected from the Options->Phone Settings... option within Articulation.

Important Note: Not all VoIP providers support GSM (in which case you must have G.711 enabled).

Network Type & Bandwidth	G.711 Codec (~80kbps)	GSM Codec (~22kbps)
Voice Modem 56kbps down, ~33kbps up	Not possible	Although possible it is unlikely that this would work well due to other technical problems.
Broadband via WiFi/Bluetooth	May provide better quality than GSM.	Use if you experience poor voice quality.
SIP Gateway on a LAN via WiFi/Bluetooth	Best solution for this network	Use if you experience poor voice quality.
GPRS^* 115kbps	Although possible, it is quite likely that other network traffic may cause some interference in speech.	Best solution for this network
EDGE^* 384kbps	Should work fine	Best solution for this speed
EVDO^* 400kbps	Should work fine	Best solution for this speed

^*Important Note: Wireless communication using the mobile telephone network often involves cost based on the amount of bandwidth used. A 3 minute 10 second GSM call can use up to 1Mb of data (for G.711, it takes only 51 seconds to use 1Mb of data). This should be taken into account when planning call costs; for example, a plan which charges $10 per Mb call costs will be over $3 per minute. Obviously a flat rate with unlimited data bandwidth would be more cost effective.