Why Voice Quality Still Matters: A Critical Differentiator in Modern Mobile Networks
- Susie S
- Apr 3
- 7 min read
Updated: Apr 4
In the ever-evolving landscape of mobile communications, where data-driven applications like video streaming and social media dominate, voice services remain a cornerstone of connectivity. Despite representing just 2% of mobile network traffic compared to the overwhelming 70% occupied by video, voice plays a pivotal role in user experience. It is the foundation of personal and professional communication, relied upon during emergencies, and remains one of the most frequently used features on mobile devices.
Voice quality remains a vital differentiator in today's evolving mobile networks. Despite a significant decrease in the proportion of voice communications—now representing roughly 2% of mobile network traffic compared to approximately 70% for video—voice service remains the cornerstone for user interactions with their devices. Subscribers often gauge the overall quality of their operator or OTT application based significantly on voice call clarity and reliability.
The Continued Significance of Voice Services
Even with the rise of video streaming, gaming, and data-centric applications, voice calls are foundational to personal and professional communications. This fundamental reliance makes voice quality a decisive factor in user satisfaction and brand loyalty. With the recent introduction of Non-Terrestrial Networks (NTNs)—like satellite connectivity—ensuring consistent voice quality has become even more complex yet critical.
Voice Quality and User Satisfaction (NPS Impact)
Quality voice service is a major driver of customer satisfaction and loyalty for mobile operators. J.D. Power emphasizes that “call quality and reliability have become the most critical drivers of customer satisfaction with network quality”
Customers now expect voice calls to be “flawless… every time”, so issues like dropouts or poor audio “substantially affect satisfaction” J.D. Power Study
In practice, carriers that deliver superior call clarity see higher satisfaction ratings. For example, the American Customer Satisfaction Index (ACSI) in 2023 showed improvements in perceived call quality: the ACSI “call quality (clarity and strength)” score for U.S. mobile operators rose from 79 to 82 (out of 100) in 2024
Top carriers AT&T and Verizon each scored 80/100 on call quality/reliability in that survey theacsi.org, indicating strong user approval of voice service.
High-definition voice technologies (e.g. VoLTE with wideband audio) are credited with boosting user experience. Industry analysts note that the enhanced voice clarity of VoLTE “improves the overall user experience, leading to higher customer satisfaction” according to Consegic Business Intelligence.
In other words, better voice quality translates into better Net Promoter Scores and loyalty. While specific NPS figures are often proprietary, telecom executives consistently rank network service quality (including voice clarity) as a top NPS driver. A Heavy Reading survey of 80 global operators found improving customer experience (closely tied to network and voice quality) was the number-one business priority and investment area
Key Factors Determining Voice Quality
Several technical factors directly influence voice quality:
Codec Quality and Efficiency: New advanced codecs offer improved audio fidelity and bandwidth efficiency but require precise implementation and management.
Network Latency and Jitter: Delays in packet transmission can significantly degrade call clarity, creating echoes and distorted conversations.
Packet Loss: Even minor packet loss can severely disrupt voice communication, making packet delivery reliability paramount.
Measuring and Troubleshooting Voice Quality
Accurately measuring voice quality involves sophisticated techniques, including:
Mean Opinion Score (MOS): An established method where human listeners rate call quality. It rates calls on a scale from 1 (bad) to 5 (excellent) based on human audio perception.
Perceptual Objective Listening Quality Analysis (POLQA): In modern testing, MOS is often obtained via objective algorithms (e.g. ITU P.863 POLQA, which predicts MOS by comparing reference and received audio). POLQA is highly precise and is used to evaluate voice quality across different technologies (2G, 3G, VoLTE, OTT VoIP, etc.)
Drive and Walk Tests: Field measurements ensure real-world verification of voice quality under typical usage scenarios.
.Operators and independent testers also measure other voice KPIs: call setup time (typically 2–5 seconds for VoLTE), call drop rates (often targeted below 0.5–1%), and coverage of HD voice.
Troubleshooting voice issues typically involves analyzing network KPIs, reviewing codec performance, and identifying areas of significant packet loss, latency, or interference
Operator vs. OTT Voice Services
The proliferation of OTT services like WhatsApp, Skype, and Zoom has reshaped the voice communication landscape, directly competing with traditional operator voice offerings.
Mobile network operators today face intense competition from OTT voice services like WhatsApp, Skype, and others. Users often compare the call quality and reliability of carrier-provided voice (circuit-switched or VoLTE/VoNR calls) against these internet-based apps. Benchmark tests indicate that operators’ dedicated voice services still hold an edge in consistency and reliability.
For instance, a 2023 in-depth drive test study in Europe compared legacy 2G calls, VoLTE calls, and WhatsApp VoIP calls using objective MOS (Mean Opinion Score) measures. The results were striking: VoLTE delivered the highest and steadiest quality, with 98% of VoLTE call samples rating “Excellent” in MOS quality (MOS ≥4.5)
By contrast, the same network using WhatsApp (OTT voice) had 64% of call samples as Excellent and a notable 16% of samples falling to “Fair” quality (MOS in the 3.0–3.9 range). This demonstrates that carrier VoLTE can provide more consistently high audio quality than OTT VoIP under the same conditions.
Comparative analyses based on real-world measurements have shown:
Reliability: Operator-managed voice services typically deliver more consistent and reliable quality due to better-controlled network conditions.
Quality: OTT services frequently adopt more advanced codecs and provide higher-definition audio, albeit often susceptible to external factors like network congestion or weaker data coverage.
User Experience: Users may tolerate variable quality from OTT apps due to their convenience and additional features like video calling and messaging integration, yet they continue to expect consistently high-quality voice calls from mobile operators.The quality of voice calls is more than just a technical metric—it is a key factor in how subscribers perceive their mobile operators and over-the-top (OTT) communication services. Whether it’s the seamless clarity of an operator's voice call or the accessibility of an OTT app, the user’s experience is heavily shaped by voice quality. With the rise of advanced technologies, including Non-Terrestrial Networks (NTNs) and modern voice codecs, the challenge of delivering and measuring superior voice quality has grown significantly.
Regional Insights and Trends
North America & Europe: These regions have nearly universal VoLTE and are now transitioning to Vo5G. Voice quality is generally consistent and high.
Asia-Pacific: A mix of ultra-advanced markets and developing ones creates varied insights.
Middle East & Africa: These regions are diverse, but many countries still rely on a mix of 2G/3G for voice alongside newer VoLTE in cities.
Latin America: Similar to MEA, with patchy VoLTE adoption but improving. Many LatAm operators report that introducing VoLTE
In all regions, a common thread is emerging by 2025: simply providing voice service is not enough – operators must provide excellent voice service. Voice is the most basic telecom offering, yet its quality can distinguish a premium operator from a mediocre one. Where they lead in voice quality, operators often incorporate that into branding (e.g. advertising fewer dropped calls, “crystal-clear” audio, or quoting awards from P3 connect or JD Power). And where they lag, churn can spike as users substitute with OTT or rival networks. Thus, investment in voice technology (from network upgrades to codecs to optimization)and thorough testing is viewed as investment in customer experience.
How SmartViser Can Help?
How SmartViser Can Help with Voice Quality Testing
SmartViser is at the forefront of enabling operators and service providers to ensure superior voice quality through its innovative testing solutions. By leveraging its automated test suite, viSer, SmartViser offers comprehensive tools and methodologies to evaluate, troubleshoot, and optimize voice performance in today’s complex mobile networks.
1. Comprehensive Testing Across Real-World Scenarios
SmartViser’s solutions are designed to simulate real-world conditions, including:
Urban and Rural Environments: Testing voice quality in diverse locations, including challenging areas like underground sites or remote regions.
Network Handovers: Evaluating call continuity and quality during transitions between network technologies (e.g., 4G to 5G).
VoLTE and VoNR Testing: Assessing the performance of advanced voice technologies and codecs like EVS under varied network loads.
2. Automated and Remote Testing
SmartViser enables operators to conduct automated voice quality tests with minimal human intervention:
Remote Testing Capability: Operators can evaluate voice services in geographically dispersed areas without needing on-site teams.
Automation for Efficiency: By automating repetitive tasks, SmartViser ensures faster, more reliable, and cost-effective testing cycles.
3. Objective Voice Quality Metrics
SmartViser integrates industry-standard voice quality evaluation methods into its testing suite:
POLQA Integration: Accurately assesses voice clarity and provides MOS (Mean Opinion Scores) to benchmark performance.
Network Metrics Analysis
4. Troubleshooting and Insights
SmartViser goes beyond identifying problems—it helps pinpoint root causes and provides actionable insights.
5. Testing OTT Voice Services
With the increasing role of OTT services, SmartViser provides tools to compare operator voice quality against popular OTT platforms, End-to-End Comparison: Benchmarks OTT services like WhatsApp, Skype, or Microfot Teams.
6. Ensuring Consistent Quality in Non-Terrestrial Networks
As NTNs become more prevalent, SmartViser’s solutions help operators ensure voice quality across satellite and hybrid networks, adapting to the unique challenges of these environments.
SmartViser’s robust and adaptable testing framework ensures that operators and service providers can deliver exceptional voice quality, maintain customer satisfaction, and stay ahead in an increasingly competitive telecommunications market. By simplifying and enhancing voice testing processes, SmartViser empowers its partners to meet the growing expectations of modern mobile users.
Susie Siouti is the Chief Commercial Officer for SmartViser helping organisations in the Telecommunications industry offer superior end-user quality of experience and service with the introduction of innovative test automation products. Susie has 20 years of experience in the Telecoms industry and in that time has led teams across the world mainly in Testing and Compliance. Holding an MBA from Henley Business School brings a diverse set of skills and expertise, including business acumen, strategic thinking, financial management, sales and marketing expertise, leadership, and innovation.
Susie joined SmartViser in 2016, is part of the internal steering committee, responsible for developing and implementing the company's commercial strategy and encouraging a customer-centric culture. The main mission is to help organizations to create value by offering better quality products and services by improving operational efficiency and innovation.
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