VoIP codec list: bandwidth, quality, and licensing

VoIP codec list: bandwidth, quality, and licensing

Voice quality can make or break your customer relationships. When your contact center agents struggle with garbled audio or when your voice AI agents sound robotic due to poor codec selection, you're not just dealing with technical issues, you're risking your reputation. With 68% of consumers preferring to communicate with businesses via phone, choosing the right VoIP codec has a direct impact on customer experience and operational efficiency. The codec challenge has intensified with voice AI adoption. Your agents, whether human or AI, need wideband support for natural conversation flow. But with dozens of codecs available, each with different bandwidth requirements, licensing terms, and compatibility issues, making the right choice can feel overwhelming.

This guide breaks down the essential VoIP codecs, comparing their bandwidth consumption, audio quality metrics, and licensing requirements. You'll learn which codecs work best for specific scenarios like remote offices, contact centers, and AI-powered deployments.

Why codec selection matters more than ever

The global VoIP services market is expected to grow from $167.3 billion in 2024 to $752.41 billion by 2034, with businesses increasingly relying on internet-based communication. Yet many organizations still struggle with codec configuration, leading to poor call quality that frustrates customers and reduces agent productivity.

The stakes are particularly high for voice AI implementations, with wideband codec making for more for natural-sounding conversations. When your AI agent uses a narrowband codec, it sounds mechanical and distant. Choose the wrong codec for your network conditions, and you'll face choppy audio that destroys the illusion of human-like interaction.

Bandwidth also plays a critical role in voice quality and system stability. VoIP calls require less than 0.5 Mbps of bandwidth for a single line according to the FCC, but this varies dramatically based on your codec choice. A G.711 call consumes 64 kbps while G.729 uses just 8 kbps, an eight-fold difference that matters when you're running hundreds of concurrent calls.

When bandwidth is tight, use highly efficient codecs like G.729 for internal calls or backup channels. Reserve higher‑bandwidth codecs like G.722 or Opus for customer‑facing lines and AI interactions where clarity and transcription accuracy matter most. That way, you preserve network capacity for the calls that make the biggest difference.

Complete VoIP codec comparison table

Here's a comprehensive breakdown of the most common VoIP codecs used in business communications:

Understanding codec specifications

Bandwidth requirements

G.711 calls typically use about 64 kbps per direction, not including network overhead, while G.729 calls use just 8 kbps per direction. But raw bandwidth tells only part of the story. When calculating actual bandwidth consumption, you must account for:

• Protocol overhead: IP/UDP/RTP headers add 40 bytes to each packet
• Packet size: Smaller packets mean more overhead as a percentage
• Network layer: Ethernet adds different overhead than MPLS or frame relay

For example, a G.729 call with voice payload size of 20 bytes (20 ms) requires 24 Kbps including headers, while doubling the payload to 40 bytes (40 ms) reduces bandwidth to 16 Kbps.

Audio quality metrics

Mean Opinion Score (MOS) grades audio quality on a scale between 1 and 5. A score above 4.0 is considered toll quality. A score below 3.5 is considered unacceptable. But MOS alone doesn't capture the full quality picture.

Wideband codecs like G.722 capture frequencies from 50-7,000 Hz, compared to narrowband's 300-3,400 Hz range. This wider frequency response makes voices sound more natural and reduces listener fatigue during long calls. That is especially helpful for contact center agents handling dozens of conversations daily.

Processing requirements

Codec complexity directly impacts your infrastructure costs. G.711 performs no compression and places very light load on processors, while G.729's compression algorithm demands more processing power. This matters when deploying thousands of endpoints or running voice AI agents that already consume significant computational resources.

Selecting codecs for specific scenarios

High-volume contact centers

Contact centers need to balance quality with efficiency. Start with G.722 for supervisor stations and customer-facing premium lines where voice clarity directly impacts satisfaction scores. Deploy G.729 for internal communications or during high-traffic periods, where slight quality reduction won't impact customer experience.

Configure your system to negotiate codecs dynamically based on available bandwidth. Use G.722 when possible, but fall back to G.729 during peak hours

Voice AI agent deployments

Opus is widely regarded as the best voice codec for VoIP in 2025, offering unmatched audio quality across a wide range of bitrates and conditions. For voice AI agents, Opus provides several advantages:

• Adaptive bitrate: Automatically adjusts to network conditions
• Ultra-low latency: Essential for natural conversation flow
• Superior packet loss handling: Maintains quality even in challenging network conditions

When Opus isn't supported, fall back to G.722 for wideband quality or G.711 for maximum compatibility. Never use G.729 for voice AI agents, the compression artifacts make synthetic voices sound even more artificial.

Remote and branch offices

Remote sites often face bandwidth constraints and variable network quality. Implement a tiered approach:

1. Primary codec: G.729 for efficient bandwidth usage
2. Fallback option: G.711 for compatibility with legacy systems
3. Quality enhancement: Enable G.722 for executive communications

iLBC offers excellent toll-quality voice for very low bitrate and employs graceful speech quality degradation to deal with lost frames, making it ideal for locations with unstable connections.

International communications

Cross-border calls require careful codec selection to minimize latency and transcoding. North America and Japan use G.711 μ-law while European countries use G.711 A-law. Configure your system to:

• Match the destination network's preferred codec
• Avoid multiple transcoding hops that degrade quality
• Use G.729 for cost-effective international routes while maintaining acceptable quality

Licensing considerations and costs

The licensing landscape has shifted significantly in recent years:

Free and open-source options

• G.711: Patents expired in 1972, completely free to use
• G.729: Patent expired in January 2017, now freely available
• G.722: Royalty-free
• Opus: Royalty-free, open-source codec
• Speex: Patent-free, open-source codec

Licensed codecs requiring fees

• G.722.2 (AMR-WB): Requires licensing for implementation
• SILK: Proprietary Microsoft codec
• Siren: Siren 7 and 14 are royalty-free, but Siren 22 requires licensing

When evaluating costs, consider that hardware manufacturers often pay license fees, so end users buying VoIP phones or gateways won't need separate licenses.

Common codec configuration mistakes to avoid

Bandwidth miscalculation

Many organizations calculate bandwidth needs based on codec bitrate alone, forgetting protocol overhead and network conditions. The G.711 voice codec actually consumes up to 85kbps of internet bandwidth. Always add a 30-40% buffer for real-world conditions.

Incompatible codec selection

G.729 is specifically designed for human speech and will corrupt fax or modem signals. Configure separate codec profiles for:

• Voice calls (G.729 or G.722)
• Fax transmission (G.711 only)
• Music on hold (avoid G.729)

Ignoring transcoding impact

G.711 copes well with multiple transcoding hops, maintaining acceptable quality when calls route between different networks. However, transcoding between compressed codecs compounds quality loss. Minimize transcoding by:

• Matching peer network codecs
• Using G.711 as a common intermediary
• Deploying edge transcoding resources

How Telnyx delivers superior codec performance

Choosing a codec is only the beginning. Telnyx's carrier-grade network addresses the complete codec challenge through intelligent infrastructure design.

• Our network supports wideband codecs and selects the best one in real time
• We transcode at the edge to preserve audio quality across devices
• For Voice AI agents, our private network colocated GPUs reduce network latency to under 200 ms while maintaining HD audio with Opus and G.722.

Implementation checklist

Before deploying your codec strategy:

Network assessment

• Measure available bandwidth during peak hours
• Test packet loss and jitter rates
• Identify bandwidth bottlenecks

Codec configuration

• Set primary and fallback codec preferences
• Configure separate profiles for voice, fax, and music
• Test interoperability with partner networks

Quality monitoring

• Establish MOS baselines for each codec
• Monitor transcoding frequency
• Track customer satisfaction scores by codec type

Licensing compliance

• Audit current codec usage
• Verify licensing for proprietary codecs
• Document open-source codec versions

Moving forward with confidence

Codec selection shapes every conversation your business has. The right configuration balances quality, bandwidth, and cost while ensuring compatibility across your communication ecosystem. Whether you're optimizing a contact center, deploying voice AI agents, or connecting remote offices, understanding codec capabilities and limitations guides better decisions.

With North America holding the largest VoIP market share at 34.8% and growing, businesses that master codec optimization gain competitive advantage through superior call quality and operational efficiency.

Start by auditing your current codec configuration. Identify where narrowband codecs limit quality and where wideband codecs consume unnecessary bandwidth. Test Opus for voice AI agents and G.722 for critical customer interactions. Most importantly, work with a provider like Telnyx that handles codec complexity through intelligent infrastructure, letting you focus on what matters: exceptional customer conversations.

Ready to experience the difference that optimized codec selection makes? Contact Telnyx to discuss how our carrier-grade network with wideband support and edge transcoding can improve your voice quality while reducing costs.