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The Pipeline tab has three model sections. Each needs at least one model:

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Choose a model

Select a model row to open the model picker.
Select LLM panel listing models with their provider, Inference badge, latency, and cost per minute
You can search, and filter by:
  • Model Type:
    • Audio LLMs listen and speak directly, without separate STT and TTS. Choosing one makes the pipeline realtime.
    • Text LLMs work with the STT and TTS models you select.
  • ZeroRuntime Inference: shows only models hosted by Zero Runtime.
Each model card shows its approximate latency and cost per minute. After you pick a model, the builder walks you through any remaining steps:
1

Advanced settings

Shown only if the model supports extra settings. See Advanced settings below.
2

Language

Choose the language the model should understand or speak.
3

Voice

For TTS and realtime models, browse voices with filters (gender, age, accent, and category) and play previews.
4

API key

For models without the Inference badge, choose or add a secret holding your provider API key. See Use your own API keys.
Models with the ⚡ Inference badge are hosted by Zero Runtime. They need no provider API key, and their usage is billed to your Zero Runtime balance.
To change a model later, open the row’s ⋮ menu. From there you can change the model, languages, voice, or advanced settings, or remove a fallback.

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Fallback models

Add up to two fallback models for each section with Add fallback LLM, Add fallback TTS, or Add fallback STT. If the Primary model’s provider is unavailable, the agent tries the fallbacks in order, so the conversation keeps going.
  • Choose fallbacks from different providers than the primary.
  • With two fallbacks, drag them to change the order.
  • A realtime (audio) primary LLM can’t have fallbacks.

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Advanced settings

Settings, ranges, and defaults depend on the model. Common ones are:
Add product names and other jargon to Custom Vocabulary so the STT model recognizes them. Use Pronunciation so the TTS model says them correctly.

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Use your own API keys

Models with the ⚡ Inference badge need no key. To use a model from your own provider account, such as OpenAI, Anthropic, Google, Deepgram, Cartesia, or ElevenLabs, store its API key as a secret.
1

Open the Secrets Library

Select Secrets in the builder header. Search for a provider, or filter by Type (Audio LLM, Text LLM, STT, or TTS).
2

Add a secret

Select Manage Keys next to the provider, then Add Secret. Enter a Secret Name (for example Production key), the API Key, and optional tags. Then select Save Secret.
3

Use it

When you pick a non-inference model, the builder asks you to choose one of the provider’s secrets.
Keys are encrypted and never shown again. To change a key, edit the secret and enter the key again. Secrets in use show an Assigned badge.
Deleting a secret stops every agent using it from working until you select another key.