### Answer For a Dutch voice agent on Retell, the optimal model depends on your priorities: For best balance of speed and intelligence (recommended for real-time voice) : - GPT-4.1 Mini at $0.016/min offers low latency (~550ms) and is optimized for instruction-following and scale [(1) ]() [(2) ]() - *GPT-5 Mini (minimal) * at $0.012/min provides higher intelligence with medium latency (~800ms) [(2) ]() For high-intelligence, complex workflows: - GPT-4.1 at $0.045/min with ~720ms latency and exceptional reasoning capabilities [(1) ]() [(2) ]() - *GPT-5 (minimal) * at $0.04/min offers slightly higher intelligence but with higher latency (~1000ms) [(2) ]() For cost-sensitive high-volume use: - GPT-5 Nano at $0.003/min is the cheapest while maintaining high intelligence - GPT-4.1 Nano at $0.004/min offers low latency (~500ms) Key consideration for Dutch: GPT-4.1 was specifically noted to have a 1M token context window and support for multilingual communication [(1) ]() . The voice quality will also depend on your TTS provider selection (ElevenLabs multilingual models like

eleven_multilingual_v2

support Dutch) [(3) ]() . For most real-time Dutch voice agent use cases, GPT-4.1 Mini or GPT-5 Mini offer th

e best balance of speed, intelligence, and cost [(2) ]() .

​ To learn more, see the sources I considered: [[1] Smarter AI Phone Calls with ChatGPT-4.1 | Retell AI | Retell AI](https://www.retellai.com/blog/chatgpt-4-1-ai-phone-calling-retell) [[2] Retell AI Launches GPT-5 for Voice Agents – Higher Intelligence, Smarter Conversations | Retell AI](https://www.retellai.com/blog/gpt-5-now-on-retell-smarter-ai-voice-agents-with-reasoning-power) [[3] Create Voice Agent](https://docs.retellai.com/api-references/create-agent) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer I don't have specific information about a "4.1 Mini Fast" variant in the available sources. The documentation references the following GPT-4.1 models: -

gpt-4.1

-

gpt-4.1-mini

-

gpt-4.1-nano

[(1) ]() The available model options listed in the API don't include a separate "4.1 Mini Fast" designation. If you're seeing "4.1 Mini Fast" as an option in the Retell dashboard, this may be a newer variant or UI naming convention not yet reflected in the documentation I have access to. Check out these potentially useful sources: - [Get Retell LLM]() - [OpenAI 4.1, Version Control, and More Languages Support]() - [Smarter AI Phone Calls with ChatGPT-4.1 | Retell AI | Retell AI]() Would you like me to try to answer generally based on my broader knowledge of model variants?

​ To learn more, see the sources I considered: [[1] Get Retell LLM](https://docs.retellai.com/api-references/get-retell-llm) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer I don't have specific information about a "5.1 Mini" model in the available sources. The documentation references the following GPT-5 mini variants: - *GPT-5 Mini (minimal) * - a reasoning model [(1) ]() - *GPT-5 Nano (minimal) * - a reasoning model The API also lists

gpt-5.1

and

gpt-5.2

as available options for post-call analysis, but not as "5.1 mini". [(2) ]() Comparing GPT-4.1 Mini vs GPT-5 Mini: - **GPT-5 Mini (minimal) **: $0.012/min, ~800ms latency, highest intelligence in the lightweight group, reasoning model [(1) ]() - **GPT-4.1 Mini**: $0.016/min, ~550ms latency, no-reasoning text-first LLM For Dutch (a complex language) : GPT-5 Mini offers higher intelligence due to its reasoning capabilities, which can help with nuanced language understanding. However, it has higher latency (~800ms vs ~550ms) . The recommendation from the documentation states: "For small tasks that still benefit from reasoning, GPT-5 Mini is a strong choice. But if your workflow is speed-sensitive and doesn't require deep reasoning, stick with GPT-4.1 Mini." For complex Dutch conversations requiring nuanced understanding, GPT-5 Mini may provide better results due to its reasoning capabilities, though at the cost of slightly higher latency.

​ To learn more, see the sources I considered: [[1] Retell AI Launches GPT-5 for Voice Agents – Higher Intelligence, Smarter Conversations | Retell AI](https://www.retellai.com/blog/gpt-5-now-on-retell-smarter-ai-voice-agents-with-reasoning-power) [[2] Update Voice Agent](https://docs.retellai.com/api-references/update-agent) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer I don't have specific information about "5.1 Mini" or "5.1 Nano" models in the available sources. The documentation references: GPT-5 variants available: -

gpt-5

-

gpt-5.1

-

gpt-5.2

-

gpt-5-mini

-

gpt-5-nano

[(1) ]() Documented comparison for GPT-5 Mini vs GPT-5 Nano: | Model | Type | Intelligence | Latency | Pricing | |-------|------|--------------|---------|---------| - **GPT-5 Mini (minimal) **: Reasoning model, highest intelligence in lightweight group, ~800ms latency, $0.012/min [(2) ]() - **GPT-5 Nano (minimal) **: Reasoning model, high intelligence, ~700ms latency, $0.003/min Key differences: - GPT-5 Mini has higher intelligence than GPT-5 Nano - GPT-5 Nano has slightly lower latency (700ms vs 800ms) - GPT-5 Nano is significantly cheaper ($0.003/min vs $0.012/min) The recommendation states: "If cost is the top priority, GPT-5 Nano offers the cheapest price while still maintaining high intelligence." The API lists

gpt-5.1

and

gpt-5.2

as options, but I don't have documentation on "5.1 Mini" or "5.1 Nano" specifically. [(1) ]() [(3) ]()

​ To learn more, see the sources I considered: [[1] Get Agent Versions](https://docs.retellai.com/api-references/get-agent-versions) [[2] Retell AI Launches GPT-5 for Voice Agents – Higher Intelligence, Smarter Conversations | Retell AI](https://www.retellai.com/blog/gpt-5-now-on-retell-smarter-ai-voice-agents-with-reasoning-power) [[3] Update Voice Agent](https://docs.retellai.com/api-references/update-agent) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer Ik heb geen specifieke informatie over "gpt-5.1-mini" in de beschikbare bronnen. De API documentatie toont de volgende beschikbare modellen: [(1) ]() [(2) ]() Beschikbare GPT-5 varianten: -

gpt-5

-

gpt-5.1

-

gpt-5.2

-

gpt-5-mini

-

gpt-5-nano

Voor een complexe prompt van 9000 tokens met verschillende scripts/taken voor verschillende soorten bellers, zou je kunnen overwegen om LLM States te gebruiken. [(1) ]() [(3) ]() Met LLM States kun je je conversatie opdelen in verschillende staten, elk met een eigen prompt en tools. Dit helpt om: [(1) ]() - De prompt lengte per state te verkorten - Het aantal tool keuzes te beperken - Hallucinaties te minimaliseren doordat de LLM beter kan focussen Voorbeeld structuur:

json
"states": [
  {
    "name": "information_collection",
    "state_prompt": "You will follow the steps below to collect information...",
    "edges": [
      {
        "destination_state_name": "appointment_booking",
        "description": "Transition to book an appointment."
      }
    ]
  }
]

Dit kan effectiever zijn dan één grote prompt van 9000 tokens, ongeacht welk model je kiest. Check out these potentially useful sources: - [Create Retell LLM]() - [Platform Changelogs | Retell AI]() Wil je dat ik algemeen antwoord geef op basis van mijn bredere kennis over modelkeuze voor complexe prompts?

​ To learn more, see the sources I considered: [[1] Create Retell LLM](https://docs.retellai.com/api-references/create-retell-llm) [[2] Get Retell LLM](https://docs.retellai.com/api-references/get-retell-llm) [[3] Update Retell LLM](https://docs.retellai.com/api-references/update-retell-llm) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.