Telnyx Speech-to-Text Review

What Is Telnyx Speech-to-Text?

Telnyx is a communications platform that owns its carrier infrastructure end-to-end — SIP trunking, voice APIs, SMS, and now speech-to-text. Unlike standalone STT providers like Deepgram or AssemblyAI, Telnyx built its transcription engine to sit directly on the phone call pipeline. Audio never leaves the Telnyx network, which reduces latency and simplifies architecture for telephony-heavy applications.

The STT service handles real-time and batch transcription for phone audio specifically. If you're already running voice calls through Telnyx, adding transcription is a configuration change rather than a new vendor integration.

Pricing: Among the Cheapest Per-Minute Rates

Telnyx offers two tiers. The Basic plan starts at $0.01 per minute for standard (non-real-time) transcription with basic support. The Pro plan costs $0.05 per minute and includes real-time streaming transcription, priority support, and advanced integrations. There are no monthly minimums or seat licenses — you pay strictly for minutes processed.

At $0.01/minute, the Basic tier undercuts most competitors. Deepgram starts at $0.0043/minute for pay-as-you-go but requires more complex setup for telephony use cases. Google Cloud STT charges $0.006-$0.024/minute depending on model. For teams already on the Telnyx voice stack, the bundled pricing eliminates the overhead of routing audio to a separate STT provider.

Telephony-First Architecture

The key differentiator is network ownership. Telnyx controls the carrier layer, so phone audio flows directly from the call into the transcription engine without intermediary hops. This matters for latency-sensitive applications like live agent assist, where a 200ms delay in transcription can break the workflow.

The architecture also means you can bundle voice, SMS, fax, and STT under a single vendor and a single API key. For contact center teams managing multiple communication channels, consolidating vendors simplifies billing and troubleshooting.

Developer Experience and SDKs

Telnyx provides SDKs in Python, Node.js, Ruby, Go, and Java. The API follows RESTful conventions, and webhook-based delivery handles transcription results asynchronously. Documentation covers common telephony scenarios — recording a call and transcribing it, streaming audio for real-time results, and handling multi-party calls.

That said, the developer ecosystem is smaller than Deepgram's or AssemblyAI's. Community examples, Stack Overflow answers, and third-party tutorials are sparse. If you're not already familiar with Telnyx's API patterns, the onboarding curve is steeper than with developer-experience-focused competitors.

Language Support and Accuracy

Telnyx supports multilingual transcription for global contact center deployments, though the company doesn't publish a specific language count or accuracy benchmarks. In practice, accuracy on clear phone audio is competitive with other telephony-optimized engines, but noisy or heavily accented calls will challenge any STT system tuned for 8kHz telephony audio.

There's no custom vocabulary or domain-specific model training available as of early 2026 — a gap compared to Google Cloud STT, Azure, and Deepgram, all of which let you fine-tune recognition for industry jargon.

Use Cases Where Telnyx Makes Sense

Contact centers running on Telnyx voice infrastructure get the most value. Adding STT is a natural extension — no new vendor, no audio routing changes, no additional security review. Healthcare organizations using Telnyx for appointment reminder calls can automate voice-to-text confirmation. Financial services teams logging phone interactions for compliance benefit from keeping audio within a single network.

IVR and voice bot developers building on Telnyx can pipe call audio directly into the STT engine for real-time intent detection, keeping the entire stack under one roof.

Limitations to Consider

If you're not already using Telnyx for telephony, there's little reason to choose Telnyx STT over Deepgram, AssemblyAI, or Google Cloud STT. The transcription API is designed as an add-on to the voice platform, not as a standalone product. Language documentation is less transparent than competitors. There's no self-service model customization, no word-level timestamps in the basic tier, and no audio intelligence features like sentiment analysis or PII redaction.

How Telnyx STT Compares to Deepgram

Deepgram is the closest competitor in the telephony-optimized STT space. Deepgram offers sub-300ms latency, 36+ languages, custom model training, and a $200 free credit to start. Telnyx competes on price and on the convenience of a unified telephony stack. If you need STT as a standalone API with broad language support and developer resources, Deepgram wins. If you're already running calls through Telnyx and want to add transcription with minimal friction, Telnyx is the simpler path.

Verdict

Telnyx Speech-to-Text is a solid add-on for teams already invested in the Telnyx communications platform. The $0.01/minute starting price is hard to beat, and the carrier-native architecture eliminates audio routing complexity for phone-based use cases. As a standalone STT API, though, it lacks the language breadth, developer ecosystem, and audio intelligence features of dedicated competitors. Best for Telnyx customers building contact center or IVR applications. Skip if you need a general-purpose transcription API.