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Poor audio quality

If you experience poor audio quality when using Interaction SIP Bridge, consider the following possible causes:

Bandwidth limitations

  • Ensure that the upload speed of the Internet connection is sufficient.

    Most home-based Internet connections have an upload bandwidth limit.In some situations, this limit may be as restrictive in comparison to the download bandwidth. If you generate a large amount of network traffic over your Internet connection, this traffic can impede real-time communications.

  • Ensure that an appropriate codec is being used.

    The G.711 codec provides an 8 kHz sampling frequency and uses 64 kbps of bandwidth. Other codecs, such as G.726 (32 kbps), G.729 (8 kbps), and G.723.1 (6.3 kbps) use much less bandwidth at the expense of smaller sampling frequencies. If you are having audio quality issues for a specific codec, selecting a codec that uses less bandwidth may be a solution.

  • Ensure that the LAN containing the remote computer with Interaction SIP Bridge has sufficient bandwidth available. Other systems on the LAN could transfer large amounts of data that could cause delays at the switch or wireless access point.

Quality of Service (QoS)

  • Quality of Service (QoS) must be enabled for the IP telephone, Interaction SIP Bridge (enabled by default), the SIP line in Interaction Administrator, and Interaction Media Server.

  • Ensure that the RTP QoS DSCP markings are the same for the IP telephone, Interaction SIP Bridge, and Interaction Media Server

  • Ensure that the SIP QoS DSCP markings are the same for the IP telephone, Interaction SIP Bridge, and the SIP line in Interaction Administrator.

High network latency

Latency measures the amount of time for an IP packet to reach a network node or endpoint and for the original transmitting device to receive an acknowledgement. Latency values above 150 milliseconds can result in noticeable audio problems in real-time communications. Latency values above 300 milliseconds result in severe audio problems.

Use the Windows tracert target_name command to view latency values for each node in a network connection to a specific endpoint.

Dropped packets

If IP packets containing real-time communications are being dropped somewhere along the network connection, those communications are absent when the receiving endpoint reassembles the data from the IP packets. If you are using UDP as the transport layer protocol in real-time communications, use TCP instead.

Insufficient CPU resources on the computer

Ensure that the remote computer on which Interaction SIP Bridge is functioning has sufficient CPU resources to process real-time communications. Also consider the following items:

  • For computers with multiple core CPUs, network interface card (NIC) drivers that do not support Receive Side Scaling (RSS) process all network communications through a single CPU core. If the computer is processing a large amount of network communications and other CPU-intensive tasks, the single CPU core could reach 100% usage, which would then limit the processing speed of network communications.

  • Use Windows Task Manager to ensure that no active CPU-intensive processes are set with a higher priority than the InteractionSIPBridge.exe process, which has a default priority of Above Normal.