> ## Documentation Index
> Fetch the complete documentation index at: https://www.bolna.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Audio is choppy, robotic, or only one side can hear

> Diagnose choppy, robotic or one-way audio on Bolna Voice AI calls across buffer size, telephony provider and SIP trunk configuration.

Audio faults are almost always carrier or transport problems, not agent configuration. Establish which of the three symptoms you have before changing settings.

## First, classify the symptom

| Symptom | Most likely cause |
| - | - |
| Agent audio stutters or drops syllables | Buffer size too low, or packet loss on the carrier leg |
| Agent sounds robotic or metallic throughout | Voice model or codec, not the network |
| Caller hears the agent but the agent hears nothing (or vice versa) | One-way media — SIP or NAT configuration |
| Audio is fine on some calls and bad on others, in one region | Carrier routing for that region |

***

## Choppy or stuttering agent audio

<Steps>
  <Step title="Raise buffer size">
    On the [Languages tab](/docs/agent-setup/audio-tab), increase **Buffer Size**. Values between **150 and 250** work for real-time conversation; lower values start playback sooner but break up under any jitter.
  </Step>

  <Step title="Check whether it correlates with a provider">
    Compare recent calls in [Call history](/docs/agent-setup/call-history). If choppiness clusters on one telephony provider or one destination country, it is a carrier issue — see [Choose a telephony setup](/docs/supported-telephony-providers).
  </Step>

  <Step title="Try a lower-latency voice model">
    Heavier TTS models are more sensitive to timing. A turbo or low-latency model from the same provider usually removes the stutter.
  </Step>
</Steps>

<Warning>
  Raising buffer size trades delay for smoothness. If callers then complain the agent is slow to reply, you have moved the problem — see [Responses feel slow](/docs/concepts/latency).
</Warning>

***

## One-way audio

One-way audio on a **bring-your-own-trunk** setup is nearly always media negotiation. Work through:

<Steps>
  <Step title="Verify the trunk is registered and reachable">
    Re-check the trunk against [Set up and register your trunk](/docs/sip-trunking/byot-setup).
  </Step>

  <Step title="Confirm media is allowed in both directions">
    Firewalls that permit SIP signalling but not RTP produce exactly this symptom. Open the media ports your SBC uses, in both directions.
  </Step>

  <Step title="Check codec overlap">
    If the two sides share no codec, the call connects and stays silent.
  </Step>

  <Step title="Test the same agent on a Bolna-managed number">
    If audio is clean there, the agent is fine and the trunk is the variable. See [Place calls on your trunk](/docs/sip-trunking/byot-outbound-calls) and [Receive calls on your trunk](/docs/sip-trunking/byot-inbound-calls).
  </Step>
</Steps>

***

## Background noise, not audio faults

If callers complain the agent's line "sounds noisy", check whether **ambient noise** is enabled on the [Call tab](/docs/agent-setup/call-tab) — it plays a background track deliberately, and is available on Plivo and Vobiz telephony. Set it to **None** to remove it.

***

## What to collect before contacting support

* The `execution_id` of two bad calls and one good one
* The telephony provider and destination country
* Whether the fault is inbound, outbound, or both
* For SIP trunks, a SIP trace covering the failing call

Then reach out through [Get help](/docs/getting-help).


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