Codecs
g729 is a low bandwidth codec that is best suited to run over low speed 3g mobile networks. g711 is a higher bandwidth codec that is best suited for wired Ethernet, WiFi, and mobile 4g networks. g711 will provide the best voice quality, but it will be at the cost of higher bandwidth usage. Some softphone clients allow the selection of codecs allowed per network type. If you are unsure of which codec to select, g729 offers a good balance between bandwidth usage and quality. If overall sound quality is top concern, use g711.