Today we’re introducing Ruby Voice, the voice model behind every call Heyno answers. It is built for one job: sounding like a person on a real phone line, where the caller is in a truck, the line is noisy, and nobody waits politely for a model to finish thinking.

Built for the phone, not the demo

Most voice stacks chain three models together: one to transcribe, one to think, one to speak. Every hand-off costs time, and the caller hears all of it. Ruby Voice is a single model with speech in and speech out, so a turn comes back in a fraction of a second.

  • Noise is normal. Trained on calls from trucks, job sites, and speakerphones, not studio audio.
  • Barge-in built in. It stops when the caller starts talking, the way people do.
  • Your voice, consistently. Tone and greeting stay the same on the thousandth call.

Latency you can hear

On the phone, the gap before a reply is the whole experience. Under 300 ms feels like a conversation; past a second the caller starts talking over you.

Voice turn latency: speech in to speech out
Median milliseconds on live PSTN calls. Lower is better.
Voice turn latency, median milliseconds02414817229631204290Ruby Voice340Ruby-Horizon760Chainedstack A1020Chainedstack B
Latency across percentiles
A single model with speech in and speech out, without hand-offs between stages.
Latency by percentile0ms400ms800ms1200ms1600ms2000msp50p75p90p95p99Chained stackRuby Voice

Interruptions and handoff

Ruby Voice yields the moment a caller cuts in, and it knows when the call has stopped being its job: a price dispute, an upset customer, anything outside the rules you set. It hands off to a person with the context already summarized, and texts you what happened.

Voices and languages

CapabilityDetail
VoicesA set of natural voices; pick one per number or per team
LanguagesEnglish and Spanish today, with more in preview
Bilingual callsSwitches language mid-call when the caller does
Custom greetingYour own opening line, spoken the same way every time

Availability

Ruby Voice powers Frontdesk on every paid plan, and it is the voice inside Ruby-Horizon for approved enterprise deployments. Personal accounts get it for their own calls in the app. See Models for how to choose.

Written by

Heyno

2026