Production health for voice AI agents.

Zelto listens to every call, diagnoses what broke, and tells you exactly how to heal your agents. Every fix compounds.

01Listen
  • call_a1b2c31:24
    vapiOutbound Sales
  • call_d4e5f60:48
    retellRenewals · EN
  • call_g7h8i92:11
    livekitTriage IVR
02Diagnose
Listen
to every call
Detect
issues + improvements
Group
calls that share the issue
Rank
findings by call volume
03Heal
  • highF-104247 calls

    Voicemail not detected · payment data leaked

  • mediumF-104323 calls

    Agent narrated "pressing 2" instead of DTMF tone

  • lowF-104412 calls

    Number enunciation glitch: "2,400 2,400"

Each fix moves a number on your dashboard.

Findings closed become agent improvements. Agent improvements become metrics: collections, sales, first-call resolution. The same numbers you already report on, going in the right direction.

  1. 01

    Calls in

    • vapi · 0:42
    • retell · 1:18
    • livekit · 2:03
    • vapi · 0:54
    • bland · 1:51
    • vapi · 1:09
    • retell · 0:38
    • pipecat · 2:24

    Every production call streamed in real time

  2. 02

    Diagnosed

    Clusters detected146 calls
    • Voicemail not detected47
    • DTMF narrated, not sent23
    • Number stutter on amounts12
    • Greeting too slow8
    • Missed customer interrupt18
    • Hallucinated callback time6
    • PII read pre-auth9
    • Compliance disclosure skipped11
    • Wrong date format readback7
    • Long pause after price5

    Zelto detects issues and groups every call that shares the same one

  3. 03

    Findings

    • highF-104247 calls

      Voicemail not detected · payment data leaked

    • mediumF-104323 calls

      Agent narrated key press instead of DTMF

    • lowF-104412 calls

      Number enunciation glitch on dollar amounts

    • highF-10459 calls

      PII spoken before caller authentication

    • mediumF-104614 calls

      Greeting tempo drifts after 30s of silence

    • lowF-10476 calls

      Regional last name confuses TTS

    • highF-104811 calls

      Missed required compliance disclosure

    • mediumF-104917 calls

      Callback time committed agent can't honor

    • lowF-10508 calls

      Date repeated back in wrong format

    • mediumF-10515 calls

      Long pause after price quote

    Ranked by how many calls are affected. Fix the patterns, not the noise

  4. 04

    Outcomes

    Last 30 days
    • +12%
      Collection rate
    • +8%
      Sales conversion
    • +18%
      First-call resolution
    • −37%
      Bad calls / day
    • +9%
      CSAT
    • −14%
      Avg. handle time
    • −52%
      Compliance flags
    • −21%
      Refund requests
    • +22%
      Containment
    • −28%
      Escalations
    • −16%
      Repeat callers
    • −9%
      Avg. quote-to-close

    The metric your business runs on starts moving

More than just findings.

Findings sit at the center of Zelto. The parts around them are what make the system land in your team's actual workflow.

Findings · last 30 days6 shown
  • highF-1042Voicemail not detected · payment data leaked47
  • mediumF-1043Agent narrated key press instead of DTMF23
  • mediumF-1044Greeting tempo drifts after 30s of silence14
  • lowF-1045Number enunciation glitch on dollar amounts12
  • highF-1046PII spoken before caller authentication9
  • mediumF-1047Callback time committed agent can't honor17

Findings

Every recurring failure, grouped by the calls that share it.

Zelto clusters every call that fails for the same reason into one Finding, ranked by call volume. Fix the patterns that touch the most production traffic first.

Linear · ENG-217
mediumF-091734 calls

Fix: acknowledge frustration before offering next steps

prompt.system · diff
"I'm sorry, I can't help with that."
"I hear how frustrating this is. Let me try a different path to get this sorted for you."
Hand the patch to

Fix

Drafted fixes, ready for your agent.

Every finding ships with a prompt and a Linear ticket. Hand it off to Claude, Codex, Cursor, or whatever coding agent you already use.

#customer-acme-inc
ZeltoApp2:14 PM
Tool call failed on a high payment intent user
tool.charge_card · timeout after 4.8s
State: NewSeverity: HighCustomer: Acme Inc

Alerts

Per-customer alerts in Slack.

Route findings to a dedicated channel per customer. The team that owns the account hears about a regression the moment it happens.

Which agent regressed this week?
Sales Outbound. F-1042 went from 4 to 47 calls after Tuesday's prompt update.
Show me the diff

Ask Zelto

An AI that knows your voice ops.

"Which agent regressed this week?" The in-product copilot answers in plain English.

0:00▶ 0:42 – 0:481:24

Listen to the moment

Jump to the failing seconds, not the full call.

Each finding pins the exact range that triggered it.

Reviewer feedback
highlowF-211412 calls

Greeting tempo drifts after 30s of silence

Diego: Not an issue for collections. Lower severity, our greetings need room.
Zelto re-graded 14 similar calls

Learning

Gets sharper every time your team gives feedback.

Mark a finding wrong or lower its severity. Zelto applies the correction across every call that shares the pattern.

One API, every voice stack you already use.

Native integrations with the big voice platforms. Or connect using our API.

Read the docs
  • Vapi
  • Retell
  • Bland
  • ElevenLabs
  • LiveKit
  • Pipecat
  • Telnyx
  • Custom / API
  • Vapi
  • Retell
  • Bland
  • ElevenLabs
  • LiveKit
  • Pipecat
  • Telnyx
  • Custom / API
Mozart

Voice AI debt collection startup

“Zelto reduces the time our engineers and solution architects spend reviewing calls, now they can focus on making the agent for our customers better.”
Diego Sanchez
CTO & Founder, Mozart

What you'll ask us.

The questions that come up on every first call. Answered honestly.

One week. One agent. Ten findings.

Connect one production agent. We listen for a week, then walk you through ten findings with severity, examples, and fixes. No commitment after.

Get a Demo