Podcast Ep. 6: VoIP MOS Score: What It Means and How to Fix Bad Call Quality
Episode 6 of ViciStack Call Center Tech -- the VoIP call quality episode for people who are tired of agents saying "the phones sound bad." MOS scores, jitter, packet loss, latency -- these terms get thrown around a lot, but most call center operators don't know what they actually mean or how to fix them. This episode translates the ITU standards into plain-English troubleshooting for Asterisk and VICIdial environments. --- Duration: 6:03 Subscribe via RSS to get notified when this episode goes live on Podbean. --- - 0:00 -- Intro: Why agents complain about call quality and what MOS means - 0:45 -- The MOS scale: 1.0 to 5.0 and what each range sounds like - 1:35 -- ITU-T P.800 methodology and how measurement actually works - 2:25 -- Measuring VoIP quality: RTCP stats,...
Overview
Episode 6 of ViciStack Call Center Tech -- the VoIP call quality episode for people who are tired of agents saying "the phones sound bad."
MOS scores, jitter, packet loss, latency -- these terms get thrown around a lot, but most call center operators don't know what they actually mean or how to fix them. This episode translates the ITU standards into plain-English troubleshooting for Asterisk and VICIdial environments.
Listen Now
Duration: 6:03
Subscribe via RSS to get notified when this episode goes live on Podbean.
Timestamps
- 0:00 -- Intro: Why agents complain about call quality and what MOS means
- 0:45 -- The MOS scale: 1.0 to 5.0 and what each range sounds like
- 1:35 -- ITU-T P.800 methodology and how measurement actually works
- 2:25 -- Measuring VoIP quality: RTCP stats, Asterisk CLI, network tools
- 3:15 -- Jitter, packet loss, and latency thresholds for call centers
- 4:10 -- Codec selection: G.711 vs G.729 and impact on MOS
- 4:55 -- QoS configuration for VICIdial networks
- 5:30 -- Quick wins for improving call quality today
- 5:55 -- Outro
Key Takeaways
- MOS 4.0+ is the target for call centers. Below 3.5, calls sound noticeably degraded. Below 3.0, agents and prospects both have trouble understanding each other. Aim for 4.0-4.3 on every trunk.
- Jitter kills call quality faster than latency. 150ms of consistent latency is workable. 30ms of jitter is not. Jitter buffers help, but only if you configure them -- Asterisk defaults are often too small for high-volume environments.
- G.711 gives better quality but uses more bandwidth. For local trunks and LAN agents, always use G.711 (ulaw/alaw). G.729 saves bandwidth for remote/WAN connections but drops your MOS ceiling by 0.3-0.5 points.
- QoS tagging is pointless without end-to-end enforcement. DSCP marking on your VICIdial server does nothing if your ISP or the carrier's network ignores it. Verify QoS is honored at every hop.
- The fastest fix is usually the network, not the software. Dedicated VLAN for voice traffic, wired (not Wi-Fi) connections for agents, and a separate ISP circuit for SIP trunks solve 80% of call quality complaints.
Read the Full Article
The full written guide includes Asterisk CLI commands, network diagnostic tools, and QoS configuration examples:
VoIP MOS Score: The Complete Guide
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Resources
- Read the full article on ViciStack
- ViciStack - VICIdial hosting and optimization
- Free VICIdial Audit