Block Error Rate (BLER) Metric

Overview

Block Error Rate (BLER) measures the percentage of erroneous or unintentional blocks that occur on a digital circuit compared to the total number of blocks transmitted. In call centres and telecommunications environments, blocks represent data transmission units or call interruptions. Tracking this metric helps teams distinguish between intentional system controls and accidental errors, providing a clearer picture of actual network or system performance.

Understanding your block error rate is essential because it reveals whether performance issues stem from system design or genuine technical failures. A high error rate signals problems that need investigation, while a low rate confirms your systems are operating reliably.

Why block error rate matters

Call centre managers and telecommunications teams rely on block error rate to assess system health and reliability. When blocks occur unexpectedly, they disrupt service quality and customer experience. By monitoring this metric, you can:

• Identify systemic issues: Distinguish between planned blocks (intentional system controls) and unplanned ones (errors).
• Improve reliability: Track whether your infrastructure improvements are reducing accidental blocks over time.
• Support compliance: Maintain records of system performance for regulatory or internal quality standards.
• Optimize resource allocation: Focus troubleshooting efforts on the root causes of errors rather than treating all blocks equally.

How to calculate block error rate

Formula:

(Erroneous blocks ÷ Total number of blocks) × 100 = Block Error Rate (%)

Example: If your system processes 10,000 blocks in a month and 450 are erroneous, your block error rate is (450 ÷ 10,000) × 100 = 4.5%.

Block error rate benchmarks and targets

Most call centres and telecommunications operations aim for a block error rate below 5%. A target of 5% or lower indicates acceptable system performance. However, industry standards vary by sector:

• Telecommunications networks: Often target 1–3% to maintain service quality.
• Call centre operations: Typically aim for 3–5% depending on system age and infrastructure.
• Legacy systems: May have higher acceptable thresholds (5–10%) due to equipment limitations.

Set your target based on your system's capabilities, customer expectations, and industry benchmarks. Review and adjust targets quarterly as you implement infrastructure improvements.

Who should monitor block error rate

• Call centre managers: Monitor overall system performance and identify when technical issues affect agent productivity.
• Network or IT teams: Use this metric to prioritize maintenance, upgrades, and troubleshooting.
• Quality assurance teams: Track whether system reliability improvements are working as intended.
• Operations leaders: Review trends to forecast infrastructure needs and budget for upgrades.

Reporting frequency

Most organisations review block error rate monthly, though some high-volume telecommunications environments monitor it weekly or even daily to catch emerging issues quickly.

Related metrics to track alongside block error rate

To get a complete picture of system health, pair block error rate with these complementary metrics:

• Service level: The percentage of calls answered within your target time threshold.
• First contact resolution (FCR): The percentage of customer issues resolved on the first call.
• Average handle time (AHT): The average duration of agent interactions, which can be affected by system blocks.
• Abandoned call rate: The percentage of calls dropped before reaching an agent, often linked to system reliability.
• Agent occupancy rate: The percentage of time agents spend on active calls—system blocks can artificially inflate this metric.

How to reduce block error rate

If your block error rate is trending upward, investigate these common causes:

• Network congestion: Upgrade bandwidth or implement traffic management during peak hours.
• Hardware failures: Replace aging equipment or faulty components causing intermittent blocks.
• Software bugs: Work with your vendor or development team to patch known issues.
• Configuration errors: Audit system settings to ensure blocks are configured intentionally, not by accident.
• Insufficient monitoring: Implement real-time alerting so you catch errors before they compound.