Systematic Call Quality Troubleshooting
Learn about systematic call quality troubleshooting
Why You Need a Framework
When a customer reports "bad call quality," that could mean a dozen different things. Without a systematic approach, you'll waste time chasing ghosts. This lesson gives you a repeatable framework that works for every quality complaint — from one-way audio to echo to choppy speech.
The goal is simple: isolate the leg, identify the symptom, find the cause, fix it.
The Four-Step Framework
Step 1: Isolate the Leg
Every call through Telnyx has at least two legs:
Customer A ──► Telnyx Ingress SBC ──► Telnyx Core ──► Telnyx Egress SBC ──► Customer B
Leg A (inbound) Leg B (outbound)
Your first job is to determine which leg has the problem. Ask:
- Does Customer A hear the issue, Customer B, or both?
- Is the issue present on the Telnyx-side capture (between SBCs)?
- Does the problem persist if you swap the termination route?
💡 NOC Tip: the Telnyx Mission Control portal, pull the call detail record (CDR) and look at the
leg_id. Each leg has independent RTCP stats. Compare MOS, jitter, and packet loss for Leg A vs Leg B separately — this instantly tells you which side is degraded.
Step 2: Identify the Symptom
Classify the problem into one of these categories:
| Symptom | Description |
|---|---|
| No audio | Complete silence in one or both directions |
| One-way audio | Audio flows in one direction only |
| Choppy audio | Words cut in and out, robotic sound |
| Echo | Speaker hears their own voice delayed |
| DTMF failure | IVR menus don't respond to key presses |
| Distortion/static | Garbled or noisy audio |
| Latency | Noticeable delay in conversation |
Step 3: Find the Cause
Each symptom maps to a set of likely causes. We'll cover each below.
Step 4: Fix and Verify
Apply the fix, test with a new call, and confirm RTCP stats normalize. slug: "quality-troubleshooting"
🔒 Full Course Content Available
This is a preview of the Telephony Mastery Course. The complete lesson includes:
- ✅ Detailed technical explanations
- ✅ Advanced configuration examples
- ✅ Hands-on lab exercises
- ✅ Real-world troubleshooting scenarios
- ✅ Practice quizzes and assessments
Preview shows approximately 25% of the full lesson content.