A low-cost VoIP route is not always the best route for a wholesale telecom operator. If calls frequently fail, take too long to connect or deliver inconsistent audio quality then the savings from a lower termination rate can quickly lose their value.
Quality-based routing in VoIP helps operators make smarter routing decisions by considering call performance alongside commercial factors. Instead of selecting a carrier based only on price the routing strategy can prioritize routes with stronger performance indicators such as Answer-Seizure Ratio (ASR) and Average Call Duration (ACD).
For wholesale VoIP providers managing multiple carriers and destinations this approach can improve traffic management and support more consistent service delivery. Understanding how it works also helps operators make better use of routing capabilities within platforms such as DeNovoLab Class 4 Fusion.
What Is Quality-Based Routing in VoIP?
Understanding the Core Concept
Quality-based routing is a call-routing approach that considers the performance of available carrier routes when selecting where to send a call. Its objective is to prioritize routes that demonstrate better call completion and traffic performance rather than automatically choosing the least expensive option.
A wholesale VoIP operator may have several vendors covering the same destination. Each vendor can offer a different combination of termination rates, call completion performance and network reliability.
Consider two hypothetical carrier routes. Carrier A charges $0.008 per minute and has an ASR of 35% with an ACD of 90 seconds. Carrier B charges $0.010 per minute but demonstrates an ASR of 55% and an ACD of 180 seconds.
Although Carrier A offers a lower rate Carrier B demonstrates stronger call performance in this example. Depending on the operator's routing objectives Carrier B may represent better overall value. These figures are illustrative and do not represent actual carrier performance.
Quality Versus Cost-Based Routing
Traditional Least Cost Routing (LCR) prioritizes routes according to configured cost criteria. Quality-based routing gives greater importance to performance indicators such as ASR and ACD.
Neither approach is universally better. LCR can be appropriate when cost control is the main objective while quality-oriented selection is useful when call completion and service consistency carry greater commercial importance.
The practical goal is to balance route cost with measurable performance.
Key Metrics Used in Quality-Based VoIP Routing
Quality-based routing depends on reliable traffic information. Operators need to understand which indicators reveal route performance and what each measurement actually represents.
Answer-Seizure Ratio (ASR)
ASR measures the percentage of call attempts that result in an answered call. It is commonly used to assess call completion performance.
For example, if a carrier receives 1,000 eligible call attempts and 500 are answered then its ASR is 50%.
A consistently low ASR may indicate routing problems, destination issues or unsuccessful call attempts. However ASR should be interpreted in context because busy numbers, invalid destinations and other factors can influence the result.
Average Call Duration (ACD)
ACD measures the average duration of answered calls. It can help operators identify differences in traffic performance across destinations and carriers.
For example, one route may show a high ASR but unusually short average call durations. This does not automatically mean the route is poor but it provides a reason to investigate call patterns and customer experience.
Post-Dial Delay (PDD)
PDD measures the time between initiating a call and receiving an indication that the destination is ringing or the call has been answered.
Longer PDD can create a frustrating experience for callers. Monitoring this metric can help identify routes where call setup takes longer than expected.
Additional Performance Indicators
Operators may also examine:
Call failure and release-cause patterns
Route availability and stability
Concurrent call capacity
Traffic volume and peak usage
Network latency, jitter and packet loss
Mean Opinion Score (MOS) where reliable media-quality measurements are available
These indicators provide different perspectives on performance. ASR and ACD describe call outcomes while latency, jitter, packet loss and MOS provide additional insight into media quality.
How Quality-Based Routing Works
Quality-based routing follows a decision process that uses available route information to select an appropriate carrier. The exact implementation depends on the softswitch and its routing configuration.
Step 1: Identify Available Carrier Routes
The operator configures the vendor trunks that can terminate traffic for particular destinations. Each route may have different pricing and performance characteristics.
For example, an operator serving international destinations may have three suppliers covering the same country. The routing system needs to know which trunks are eligible for each destination.
Step 2: Collect and Evaluate Performance Data
Call records and monitoring information provide the basis for evaluating route performance. Operators can review ASR, ACD, PDD and other indicators over a defined period.
Historical performance should be interpreted carefully. A route with only a small number of calls may not provide enough evidence for a reliable comparison.
Step 3: Apply Routing Criteria
The routing engine uses configured rules to determine how eligible vendor trunks are selected.
Depending on the platform this may involve:
Prioritizing higher-ASR routes
Prioritizing higher-ACD routes
Applying cost-based selection
Using static route order
Applying different routing rules to specific destinations
Some systems support weighted scoring or threshold-based selection. These are implementation-specific approaches and should not be assumed to exist in every Class 4 softswitch.
Step 4: Route the Call and Review the Result
Once a route is selected the call is sent through the chosen vendor trunk. The resulting call records can then contribute to future performance reviews.
This creates a continuous operational process: collect performance data, evaluate routes, apply routing rules, monitor call results and review performance.
The effectiveness of this process depends on accurate records and appropriately configured routing policies.
Benefits of Quality-Based Routing for Wholesale VoIP Operators
Better Call Completion Management
Prioritizing routes with stronger historical ASR can help operators make more informed carrier-selection decisions. This is particularly useful when multiple suppliers serve the same destination.
However ASR alone cannot guarantee successful calls. Operators should also review destination conditions and call failure patterns.
Improved Customer Experience
Callers generally expect calls to connect without unnecessary delay or repeated failures. Routing decisions that account for performance can help operators maintain more consistent service across their customer base.
Greater Control Over Carrier Costs
The lowest termination rate does not always produce the best commercial outcome. A slightly more expensive route may deliver stronger call completion and reduce the operational burden associated with repeated failures.
For example, an operator can compare the effective cost of completed traffic rather than evaluating suppliers only by their advertised per-minute rates.
More Informed Vendor Management
Performance reporting gives operators a clearer basis for reviewing supplier relationships. Teams can identify routes that require investigation and discuss measurable service issues with vendors.
This makes carrier management less dependent on assumptions and more closely connected to actual traffic results.
Quality-Based Routing and DeNovoLab Class 4 Fusion
Quality-based routing requires a combination of routing flexibility, performance information and operational visibility. A softswitch should help operators manage these elements without making everyday traffic administration unnecessarily complicated.
Dynamic Routing Based on Cost and Call Performance
DeNovoLab Class 4 Fusion documents dynamic routing based on cost, ASR and ACD. Its technical cookbook describes three dynamic route-selection methods:
Least Cost Routing: Selects vendor trunks according to configured cost criteria.
Highest ASR Routing: Prioritizes vendor trunks based on ASR.
Highest ACD Routing: Prioritizes vendor trunks based on ACD.
This provides operators with different ways to organize carrier selection according to their traffic and commercial objectives.
For example, an operator may use Highest ASR Routing for a destination where call completion is a priority and LCR for another destination where cost control is more important.
The appropriate strategy depends on the operator's business requirements and the quality of the available traffic data.
Routing Plans for Destination-Specific Strategies
Class 4 Fusion supports routing plans that combine static and dynamic routing strategies. Routing rules can be configured using ANI and DNIS criteria with support for failover between routing methods.
This is useful when an operator needs different strategies for different destinations or traffic sources.
For instance, one destination can use dynamic routing based on ASR while another follows a predefined static route order. If a dynamic route cannot complete a call the routing plan can direct traffic to an alternative static route.
Monitoring and Operational Visibility
Routing decisions are more effective when operators can review what happens after calls are processed.
DeNovoLab Class 4 Fusion brings switching, routing, monitoring, billing, rate generation and CDR/PCAP backup into an integrated Class 4 environment. Its CDR data includes fields such as PDD, route plan, dynamic route name, egress carrier and call duration. These records provide useful information for investigating route performance.
The key advantage is operational integration. Instead of treating routing as an isolated function operators can review traffic alongside billing and monitoring information within the same platform.
Best Practices for Implementing Quality-Based Routing
Even a capable routing engine requires careful configuration. Poorly selected thresholds or incomplete traffic data can lead to decisions that do not reflect actual route performance.
Establish Meaningful Performance Baselines
Review historical traffic before setting routing priorities. Evaluate performance by destination and carrier rather than relying exclusively on network-wide averages.
A carrier may perform well for one country but poorly for another. Destination-level analysis helps avoid treating every route as identical.
Avoid Making Decisions from Small Samples
A route that handles only a handful of calls may show unusually high or low ASR. Operators should define a minimum sample size and review performance across a suitable time window before making significant routing changes.
Balance Quality with Commercial Objectives
The highest-ASR route is not automatically the most profitable or suitable route. Compare call performance with termination cost and customer requirements.
A balanced strategy may use quality-based selection for important destinations while retaining LCR for traffic where cost efficiency is the primary objective.
Review Routing Rules Regularly
Carrier performance can change due to network maintenance, capacity constraints and destination conditions. Review routing reports and supplier performance regularly.
Also maintain failover routes where appropriate and test routing configurations before applying them to high-volume traffic.
Keep Billing and CDR Records Consistent
Accurate CDRs help teams investigate call outcomes and compare route performance with billing information. Maintaining consistent records supports both technical troubleshooting and financial review.
Conclusion: Make Smarter Routing Decisions with DeNovoLab Class 4 Fusion
Quality-based routing gives wholesale VoIP operators a way to consider call performance alongside termination costs. By evaluating indicators such as ASR and ACD operators can make more informed decisions about carrier selection and destination-specific routing strategies.
The strongest implementation combines accurate traffic records, flexible routing policies, monitoring and regular performance reviews. It should also allow operators to balance quality requirements with commercial objectives rather than relying on a single metric.
DeNovoLab Class 4 Fusion supports dynamic routing based on cost, ASR and ACD alongside static routing, routing plans and failover capabilities. Its integrated environment connects routing with switching, billing, monitoring and CDR management.
Explore how DeNovoLab Class 4 Fusion can support your wholesale VoIP operations:
Website: https://www.denovolab.com/
Technical Cookbook: https://cookbook.denovolab.com/
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