Voice quality
The following WAN technologies are commonly used with IP Telephony:
●MPLS (Multiprotocol Label Switching)
●ATM (Asynchronous Transfer Mode)
●Frame Relay
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●Internet VPNs
The first four technologies all have good throughput, low latency, and low jitter. MPLS and ATM have the added benefit of enhanced QoS. MPLS is a relatively new service offering and currently has issues with momentary outages of 1 to 50 seconds duration. The Avaya Converged Network Analyzer product can be used to improve MPLS performance.
Frame Relay WAN circuits can be difficult to use with IP Telephony. Congestion in Frame Relay networks can cause frame loss, which can significantly degrade the quality of IP Telephony conversations. With Frame Relay, proper sizing of the committed information rate (CIR) is critical. In a Frame Relay network, any traffic that exceeds the CIR is marked as discard eligible, and is discarded at the option of the carrier if it experiences congestion in its network. Because voice packets must not be dropped, CIR must be sized to maximum traffic usage. Also, Service Level Agreements (SLAs) must be established with the carrier to define maximum levels of delay and frame loss, and remediation if the
Internet VPNs are economical but more prone to quality issues than the other four technologies.
Network management is another important area to consider when implementing IP Telephony. Because of the requirements imposed by IP Telephony, it is critical to have an
Outsource companies are also available to assist other companies that do not have the resources to implement and maintain network management.
Voice quality
Voice quality is always a subjective topic. Defining “good” voice quality varies with business needs, cultural differences, customer expectations, and hardware and software. The requirements set forth are based on the
Quality is not one discrete value where the low side is good and the high side is bad. A
