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Step 1: Model providers

Every voice agent uses three kinds of AI model:

  • LLM (large language model). This is the "brain". It decides what the agent says.
  • TTS (text to speech). This turns the agent's words into a spoken voice.
  • STT (speech to text). This turns the caller's speech into text the LLM can read.

In this step you learn where to see these models and where to choose them.

Before you start

  • Sign in to Voicent and select the right workspace in the sidebar switcher.
  • Have access to your workspace's Retell AI account. Retell runs your agents, so that is where each agent's model and voice are chosen.

Choose models for an agent

You pick the LLM, voice, and speech recognition model when you build the agent in Retell. You do this in Step 5: Create an agent. There is nothing to enter in Voicent first.

To check which models an existing agent uses:

  1. In the sidebar, click Voice Agents.
  2. Find your agent. Each agent card shows its LLM provider and model, and its Voice provider and voice.
  3. Click View Details to see more. The LLM Settings tab shows the Provider, Model, and Response Engine Type. If the agent has a backup model, a Fallback LLM card shows it.
  4. Open the Voice & Speech tab to see the Voice Provider and Voice ID.
  5. Open the Transcription tab to see the ASR Model (speech to text) and Language.

These fields are read-only in Voicent. To change them, edit the agent in Retell, then sync it again. See Step 5.

Explore the Model Providers page

The Model Providers page gives an overview of common AI providers.

  1. In the sidebar, click Model Providers.
  2. Use the tabs to browse LLM Providers, TTS Providers, and STT Providers. Each card lists a provider's models, typical cost, speed (latency), and supported languages.
  3. Open the Benchmarks tab to compare providers on speed and cost.

This page is for reference only

The Model Providers page shows example provider information. Its Add Provider dialog, Configure buttons, and Primary LLM and Fallback LLM choices do not change your agents yet. The onboarding wizard's Model Providers step (with LLM Provider, API Key, TTS Provider, STT Provider, and Test Connection) does not save either. Do not paste API keys into these forms. Choose models in Retell instead.

Tips for choosing models

Tip

  • Faster models usually make conversations feel more natural, because callers wait less between turns.
  • Pick a voice that matches your brand and your callers' language and accent.
  • Test a few voices in Retell before you go live.

Learn more

What's next

Set up the numbers your agent will answer: Step 2: Twilio and phone numbers.