What caused the sudden 30% increase in failed call transfers on Exotel's IVR system last week?

Introduction

The sudden 30% increase in failed call transfers on Exotel's IVR system last week is a critical issue that demands immediate attention. This analysis will systematically identify, validate, and address the root cause while considering both short-term fixes and long-term implications for our IVR system.

I'll approach this problem by first clarifying key details, ruling out external factors, and then diving deep into our product ecosystem. We'll break down the metric, gather relevant data, form hypotheses, and conduct a thorough root cause analysis. Finally, we'll develop a comprehensive plan to resolve the issue and prevent future occurrences.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent system update. Have there been any changes to the IVR system or related infrastructure in the past two weeks?

Why it matters: Recent changes often correlate with sudden performance shifts. Expected answer: Yes, there was a minor update to the call routing algorithm. Impact on approach: If confirmed, we'd focus on the update's impact and potential rollback.

• Considering the scale of the increase, I'm wondering about traffic patterns. Has there been any unusual spike in call volume or changes in call patterns recently?

Why it matters: Unusual traffic could strain the system beyond its normal capacity. Expected answer: Call volume has been within normal ranges. Impact on approach: If true, we'd shift focus from capacity issues to system-specific problems.

• Given the specificity of the issue to call transfers, I'm curious about the affected user segments. Are all user types experiencing this issue equally, or is it concentrated in specific customer segments?

Why it matters: Segmented issues often point to specific system components or user behaviors. Expected answer: The issue seems to affect all user segments equally. Impact on approach: If confirmed, we'd look at core system components rather than segment-specific features.

• Considering the potential for measurement errors, I'd like to verify our metrics. Has there been any change in how we measure or define "failed call transfers" in the past month?

Why it matters: Metric definition changes can create false alarms. Expected answer: No changes to the metric definition or measurement system. Impact on approach: If confirmed, we can trust the data and focus on actual system issues.