Quality of audio perceived by the user will first and foremost be affected by the network performance. Delays, jitter, and loss of packets can severely degrade end user experience, to an unacceptable level. There are several key components that can enable FreeSWITCH to operate more securely and efficiently: MPLS or dedicated peering connections can greatly enhance the network reliability, while Quality of Service (QoS) packet tagging and differentiating settings between your local LAN and the public WAN infrastructures will let you find the sweet point between infrastructure costs and audio quality.
QoS is a mechanism for guaranteeing that certain types of communication can be ranked for importance of delivery to ensure quality. There are multiple types of QoS that can be achieved in most network environments. Generally, QoS can be done on the physical layer (for example, guaranteeing that all phones are connected on a network that has its own cables...