Models for AI voice agents
DialLink's AI voice agent uses advanced real-time speech-to-speech AI models to process audio input, generate responses, and deliver them back in natural-sounding speech. These models are optimized for low-latency communication, helping conversations feel smooth and responsive for callers.
Difference between AI agent models
Feature | Open AI Realtime | Open AI Realtime Mini | Grok Fast | Grok Think Fast |
Response quality | More natural, nuanced, and context-aware | Clear but more straightforward responses | Good at working through multi-step tasks like handling a support request or a finance question from start to finish | Reasons through queries while speaking; trained for natural, human-like conversational patterns |
Understanding accuracy | Higher, handles ambiguity and multi-step requests | Good, best for predictable, structured queries | Very accurate at real-world customer support tasks that involve using tools (like looking up an account or updating a booking) | High accuracy on speech reasoning and agentic voice benchmarks, even in noisy or telephony conditions |
Latency (response speed) | Low | Very low (faster responses) | Very low | Very low (sub-one-second time to first audio) |
Scalability | Suitable for moderate call volumes | Ideal for large-scale call handling | Can hold very long conversations without losing track of earlier details, good for complex, high-volume tasks | Suitable for high-volume, complex conversational workloads |
Performance | Higher quality with more advanced reasoning | Optimized for simple, direct interactions | Makes far fewer factual mistakes than its predecessor, and offers two modes: one for deeper thinking, one for instant replies | Strong agentic performance, handles multi-step tool use and tasks while talking |
How to choose AI voice agent model
Each model is designed for different types of interactions.
OpenAI Realtime Mini is best for simple, high-volume scenarios. It's also more consistent and follows scripted rules and guardrails more closely, which makes it a strong fit for structured, first-line interactions such as:
First-line call handling
Call routing
Basic FAQs
Data collection
Appointment scheduling
Open AI Realtime is best for more complex, high-value conversations, such as:
Customer support with nuanced requests
Sales calls
Detailed inquiries
Complex or multi-step FAQs
Grok Think Fast is best for high-volume conversations that still require strong reasoning, such as:
Complex customer support at scale
Multi-step tool use during a call (looking up information, taking actions, and continuing the conversation without added delay)
Conversations requiring high accuracy in noisy environments or over the phone line
Workflows where fast response time and advanced reasoning are both required
Models for AI messaging agents
Text-enabled agents can be powered by the following models: GPT-5, GPT-5 Mini, GPT-5 Nano, Haiku 4.5, and Sonnet 4.5.
Differences between text agent models
Feature | GPT-5 | GPT-5 Mini | GPT-5 Nano | Haiku 4.5 | Sonnet 4.5 |
Response quality | Strong, nuanced responses for complex reasoning and agentic tasks | Clear, well-defined responses; less nuanced than GPT-5 | Simple, direct responses; limited reasoning depth | Near-frontier quality despite its small size and speed | High-quality reasoning with strong coding and agentic performance |
Understanding accuracy | High, handles ambiguity and multi-step requests well | Good, best for precise prompts and well-defined tasks | Lower reasoning depth, best for narrow tasks | High accuracy across reasoning, coding, and tool-use tasks | Highest accuracy in this set, strong on nuanced, multi-step requests |
Latency (response speed) | Moderate | Fast | Very fast | Very fast | Moderate |
Scalability | Suitable for moderate-volume, higher-value conversations | Good for high-volume, well-defined interactions | Ideal for very high-volume, simple tasks (e.g., classification) | Ideal for high-volume, real-time interactions | Suitable for moderate volumes where quality matters most |
Performance | Strong all-around reasoning and agentic performance | Balanced performance for lighter-weight reasoning tasks | Optimized for speed over depth; best for summarization and classification | Matches previous-generation Sonnet performance at a fraction of the cost and latency | Top-tier performance for coding, reasoning, and complex agent workflows |
How to choose an AI messaging agent model
Each model is designed for different types of interactions.
GPT-5 Nano is best for simple, high-volume tasks, such as:
Basic FAQ responses
Message classification and routing
Short, routine replies
GPT-5 Mini is best for well-defined, moderate-volume interactions, such as:
Structured customer inquiries
Order or appointment status updates
Routine multi-step requests with predictable patterns
GPT-5 is best for more complex, higher-value conversations, such as:
Nuanced customer support requests
Multi-step troubleshooting over text
Detailed inquiries requiring broader context
Haiku 4.5 is best for fast, high-volume conversations that still need strong quality, such as:
Real-time messaging at scale
Customer support that requires quick, accurate responses
High-volume tasks that benefit from tool use (e.g., looking up order details)
Sonnet 4.5 is best for complex, high-value conversations where accuracy matters most, such as:
Detailed technical or account-specific questions
Multi-step conversations involving tools or integrations
Conversations where getting the answer right outweighs response speed