Create a Custom Voice for Your AI Voice Agent

Automate with AI3 min readUpdated 2026-03-14

Give your AI Voice Agent a voice that matches your brand. Choose from built-in voices, upload a recording, record in your browser, or browse the ElevenLabs community voice library.

Available on: Trial (1 custom voice), Agent Max (up to 5 custom voices). Not available on Pay-As-You-Go or Agent Lite plans.

Built-In Voices

JustCall includes pre-built voices across 14 languages. To use a built-in voice:

Go to Dashboard > AI Voice Agent and select your agent.
Open the Voice tab.
Browse available voices and click Preview to hear a sample.
Select the voice that fits your use case.

Built-in voices are available on all plans, including Pay-As-You-Go and Agent Lite.

Creating a Custom Voice

Three methods to create a custom voice:

Upload a Recording

Open the Voice tab and click Create Custom Voice.
Select Upload.
Upload an MP3 file (max 5 MB).
Name the voice for easy identification.

Recording tips:

Use a quiet environment — no background noise, echo, or music
Record at least 30 seconds of natural speech
Speak in the tone and pace you want the agent to use
Avoid reading a script robotically — conversational speech produces better results

Record in Browser

Open the Voice tab and click Create Custom Voice.
Select Record.
Click the record button and speak into your microphone.
Review the recording and save.

Use a good-quality microphone. Laptop built-in microphones work but produce lower-quality clones than external microphones.

Browse ElevenLabs Community Library

Open the Voice tab and click Create Custom Voice.
Select Browse.
Search the ElevenLabs community voice library by language, accent, age, and gender.
Preview voices and select one.

Community voices are pre-trained and ready to use. They cover a wide range of accents and styles.

Voice Settings

After selecting or creating a voice, adjust these settings:

Setting	Range	Effect
Speed	Slow → Fast	Controls how quickly the agent speaks
Expressiveness	Calm → Emotional	Controls vocal variation and emphasis
Volume	Low → High	Controls output volume level

Start with default settings and adjust after test calls. Higher expressiveness works well for sales and customer engagement. Lower expressiveness suits professional and clinical settings.