PreCallAI: AI Voice Platform with 100+ Language STT
Engineer Master Labs built PreCallAI's AI call center platform end-to-end — a custom multilingual STT with ~100ms latency, Whisper Large v3 Turbo as Language ID, and a streaming voice pipeline tuned for telephony audio.
What PreCallAI was up against
PreCallAI needed a multilingual AI call center capable of handling high-volume inbound and outbound calls at telephony-grade quality. Off-the-shelf STT was either too expensive at scale, too limited in language coverage, or couldn't handle 8 kHz PSTN audio accurately enough for production. The founders had the product vision but no in-house voice AI engineering capacity to ship it.
What we built
We owned the full build end-to-end: the real-time voice pipeline (WebRTC ingress, VAD, streaming STT, LLM turn-taking, TTS egress), a custom STT model fine-tuned for telephony audio with Whisper Large v3 Turbo as the Language-ID front door. Training ran on an 8× H100 GPU cluster. The platform ships with the orchestration layer, agent builder, dashboard, call analytics, and billing. It runs on AWS with autoscaling inference workers, Redis for call-state coordination, and a clean Node.js / Python split between control plane and inference services.
What shipped
“Engineer Master Labs built our entire AI call center platform from scratch. Their STT model supporting 100+ languages transformed our business completely!”
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