How AchillesHR doubled its end-to-end hire rate with Phonic

The Challenge

Building a natural and lifelike voice experience felt like a game of whack-a-mole

In many industries, there are hundreds of qualified applicants for every role. What if you could just interview all of them? AchillesHR is building an AI-native ATS with AI recruiters that source, phone screen, and schedules applicants on behalf of companies.

For use cases like AI interviewing, having a natural and humanlike voice experience isn’t just important: it makes the phone screen possible. A jarring voice experience hurts twice: candidates drop off mid-interview, souring on the employer they were interviewing with, and the platform behind the interview takes the blame for a broken experience. An inviting, engaging voice agent does the opposite: candidates open up, share honestly, and feel genuinely understood.

Achilles knew this mattered, but building a lifelike voice agent in-house kept proving challenging. Whether it was dealing with a new language requirement, voice provider outages, handling candidates who interrupt, backchannel, or trail off mid-thought, Achilles kept trading time on their core product for tuning niche parameters of their voice stack.

It was all in-house — LiveKit Agents, ElevenLabs, Deepgram, OpenAI — and then us having to manage the voice constantly, tweaking it whenever we wanted to change things. We were having to deprioritize and prioritize things based on keeping track of evolutions in voice technology, other service providers, dealing with interruptions, dealing with different languages — all of those different things — which would mean we'd have to take a week or two pause on new feature development. Over time, we learned that one person can't just keep your voice alive."

Read Egger
Co-Founder & CEO, AchillesHR

The Solution

From experiment to production in 2 hours

After an initial demo, Ben Schoeggl (CTO and Co-Founder of Achilles) was immediately impressed with Phonic’s ability to handle interruptions, back-channeling, short utterances, and an obvious step-up in voice realism. He implemented Phonic in under 2 hours and A/B tests in production showed immediate promise.

“Our customers noticed the difference immediately and call lengths started increasing — a 10 minute phone screen can just qualify a candidate, but a 40 minute AI phone screen can actually run a skills assessment too. This wasn’t just about a more natural voice; the increase in realism unlocked a whole new suite of calls that we can run”

Read Egger
Co-Founder & CEO, AchillesHR

As Achilles transferred over all of their critical voice infrastructure, members of Phonic’s forward deployed engineering (FDE) team flew to work out of Achilles’ office for a week to audit new calls, flag areas of improvement, and help customize the models for Achilles interruption patterns.

Why were Achilles interruption patterns different? Well, in popular voice use cases like customer support, users tend to say a sentence or two. In recruiting, the AI interviewer will ask detailed questions about work experience, and candidates tend to answer in a few paragraphs, pausing mid-thought to recall details and organize their thoughts. A conventional voice stack can't tell the difference between a candidate who's finished and a candidate who's thinking; so it interrupts them mid-answer. In contrast, our voice agents actually condition on and understand your actual speech, not just the transcript; this provides the context it needs to be able to handle complex voice interactions.

As we expand globally, Phonic’s ability to converse in 50+ languages is unparalleled. I just haven’t seen that anywhere, and it lets me add in more revenue at a click of a button because now I can hire across all of these geographies.

Read Egger
Co-Founder & CEO, AchillesHR

The Outcome

2x greater end-to-end hire rate, 15% more engineering time, and a 20% greater market size

Since adopting Phonic, the Achilles team has seen:

• their own end-to-end hire rate double
• 15% more engineering bandwidth that can be devoted to their own product instead of maintaining a complex voice stack
• a 20% increase in market size because of Phonic’s multilingual support
• 40% decrease in per-minute costs compared to their LiveKit implementation

"Just like our product frees up people so they can actually make good hiring decisions and get people staffed — Phonic frees us up to be able to build for our customers constantly without worrying about the intricate details of voice."

Read Egger
Co-Founder & CEO, AchillesHR