Instead of betting your Voice AI product on a single speech engine, STT Router and TTS Router give you access to every major provider through one API with the flexibility to choose which engine handles each request.
Every Voice AI team faces the same impossible choice: pick one speech engine and bet your entire product on it. Choose Whisper for accuracy but accept slower processing. Pick Deepgram for speed but pay higher costs. Select Google for language coverage but lock into their ecosystem.
What if you didn't have to choose just one?
That's the fundamental problem STT Router and TTS Router solve. Instead of committing to a single vendor, you get access to every major speech engine through one API: and you control which engine handles each request.
Traditional speech architecture forces binary decisions. Teams building Voice AI applications must choose between competing priorities:
Accuracy vs. Speed: Whisper delivers exceptional transcription quality but processes audio in batches, introducing latency that breaks real-time conversation. Deepgram optimizes for streaming speed but may sacrifice accuracy on complex audio.
Language Coverage vs. Cost: Google STT handles over 100 languages with impressive accuracy but comes with premium pricing. Specialized providers excel in specific languages but create integration complexity.
Voice Quality vs. Response Time: ElevenLabs produces incredibly natural voices but synthesis latency disrupts conversational flow. Traditional cloud TTS services optimize for speed but deliver robotic voices that hurt user experience.
The real problem isn't choosing poorly: it's that any single choice creates vulnerabilities. When your chosen provider experiences outages, performance changes, or simply can't handle new requirements, your entire voice infrastructure becomes fragile.
STT Router and TTS Router represent a fundamental shift from vendor dependency to controlled access. Rather than locking into one provider, you access multiple engines through a unified API and select which engine handles each request.
What it is: STT Router is a unified transcription API that gives you access to leading STT engines (Whisper, Deepgram, Telnyx native, and others) through one integration: edge-hosted and co-located with telephony.
Per-request engine selection: You choose which engine to use on each request. Build your own routing logic based on your requirements:
No vendor lock-in: Your STT provider today may not be your STT provider tomorrow. STT Router means that decision requires a config change, not a code rewrite.
Automatic language detection: Available on select models (e.g., Rime v3 Arcana) for use cases where language isn't known in advance.
What it is: TTS Router is a multi-engine text-to-speech platform that unifies Telnyx's native TTS, ElevenLabs, and other providers behind a single API: edge-hosted for performance.
Per-request engine selection: Choose the right engine for each synthesis request:
Voice consistency: Maintain the same branded voice identity across all AI interactions by selecting the same voice configuration on each request.
Beyond multi-engine flexibility, STT Router and TTS Router deliver a fundamental architectural advantage: co-location with telephony infrastructure.
Traditional cloud speech services introduce unavoidable network latency. Audio must travel from your telephony provider to the speech service and back: often crossing the public internet multiple times. This round-trip adds significant delay to every transcription and synthesis request.
STT Router and TTS Router run in the same facilities where Telnyx terminates voice calls. Audio processing happens where the audio already exists, eliminating network hops between speech processing and call delivery.
Zero network hops: Other TTS providers generate audio and ship it across the internet. We generate it where the call already is.
Multi-engine speech access represents a fundamental architectural evolution. Instead of betting product success on a single vendor's capabilities, teams can build voice applications that adapt to changing requirements and optimize performance as usage patterns evolve.
This flexibility enables new approaches to voice AI development:
Looking forward, multi-engine access provides a foundation for incorporating new speech technologies as they emerge. When new STT or TTS providers offer innovative capabilities, adding them requires configuration changes rather than application rewrites.
