claude-sonnet-5 is the recommended production choice — best speed-to-quality ratio. claude-haiku-4-5-20251001 is the fastest and most cost-efficient option for high-volume agents.
Quick config
Supported models
Recommendation: Start with
claude-sonnet-5. Drop to claude-haiku-4-5-20251001 if you need lower latency or cost at scale. Upgrade to claude-opus-4-8 for complex multi-step reasoning or sensitive domains.
Key settings
Writing prompts for voice
Claude follows instructions very precisely — avoid vague phrasing.- Be explicit about format: “Respond in 1–2 sentences maximum. Never use bullet points.”
- Define your scope: “Only discuss topics related to appointment scheduling.”
- Set the persona clearly: “You are a friendly receptionist for Acme Clinic. Your name is Priya.”
Function calling
All current Claude models support function calling. Functions are defined in the Tools Tab and called automatically during conversation. See Custom Function Calls for configuration.FAQ
Which Claude model should I use for voice?
Which Claude model should I use for voice?
claude-sonnet-5 for most agents — strong instruction following at low latency. Use claude-haiku-4-5-20251001 when cost or speed is the primary constraint. Use claude-opus-4-8 or claude-fable-5 only for the most complex reasoning tasks.Why is temperature 0.2 recommended?
Why is temperature 0.2 recommended?
Lower temperature makes the model more consistent and predictable — important for scripted outbound calls. For more conversational or discovery-type agents, 0.5–0.7 is fine.
How do I reduce latency?
How do I reduce latency?
Use
claude-haiku-4-5-20251001 (significantly faster than Sonnet), keep max_tokens low (150 is a good ceiling), and write concise system prompts. See Latency for a full breakdown.Can I use my own Anthropic API key?
Can I use my own Anthropic API key?
Yes. Connect your Anthropic account at platform.bolna.ai/auth/anthropic. LLM costs will be charged to your Anthropic account.
Related
- LLM Tab — configure LLM in the dashboard
- OpenAI — GPT-5 family alternative
- OpenRouter — access Claude via unified gateway
- Prompting Guide — write effective prompts for voice
- Custom Function Calls — add tools to your agent