Grok Voice Think Fast 2.0 is xAI’s latest speech-to-speech model for automated phone calls and live voice services. It listens, responds, reasons through requests, and connects with business tools during a conversation. The model is mainly designed for customer support, sales, scheduling, reservations, and other phone-based tasks.
Key Takeaways
- Grok Voice Think Fast 2.0 was announced on July 29, 2026.
- It recorded a 0.70-second time to first audio in benchmark testing.
- The model scored 82.9% on the Artificial Analysis Speech-to-Speech Quality Index.
- xAI reports improved transcription across 24 languages.
- Grok Voice costs $0.08 per minute of audio.
- Businesses can connect it with calendars, customer records, support tools, and other software.
What Is Grok Voice Think Fast 2.0?
Grok Voice Think Fast 2.0 is a speech-to-speech model built by xAI. It takes spoken input and gives spoken answers without requiring the caller to type anything.
xAI says the new version improves response speed, transcription, reasoning, and tool use compared with the earlier Think Fast model.1
Depending on how a business sets it up, Grok Voice may be used to:
- Answer common customer questions
- Schedule or change appointments
- Check order details
- Create support tickets
- Make reservations
- Route callers to an employee
- Collect basic sales information
The model does not automatically know a company’s records or policies. A business must connect the right systems and decide what the voice agent is allowed to do.
How Does Grok Voice Work?
Many automated phone systems rely on several separate services. One turns speech into text, another processes the request, and a third turns the answer back into speech.
That process can create delays and errors, especially with names, dates, numbers, and corrections.
Grok Voice is designed to handle more of the exchange within one model. It can listen to the caller, understand the request, and begin responding while it works through the next step.
For example, a caller could say:
“Move my Tuesday appointment to Friday afternoon.”
A connected Grok Voice agent could check the calendar, find open times, and ask the caller which option works best.
Why Does Grok Voice’s Speed Matter?
Long pauses make automated calls feel awkward. Callers may think the system did not hear them, repeat themselves, or start talking over the response.
In Artificial Analysis testing, Grok Voice Think Fast 2.0 recorded a 0.70-second time to first audio.2
That does not mean every real call will have the same response time. Speed may change based on the phone system, internet connection, connected tools, and the complexity of the request.
It also does not guarantee accuracy. A fast answer is useful only when the system understands the caller and completes the right action.
How Accurate Is Grok Voice?
xAI says it tested Grok Voice Think Fast 2.0 using thousands of short phrases across 24 languages.
According to the company, the model achieved a 1.5–2.0× improvement in transcription accuracy compared with Deepgram Nova 3 and ElevenLabs Scribe v2 in its own testing.1
xAI also reported stronger performance when calls included background noise and compressed phone audio.
These are company-reported results, so businesses should still run their own tests. Real calls may include strong accents, poor signals, people speaking quickly, or several voices in the background.
What Do the Grok Voice Benchmarks Show?
Artificial Analysis compares speech-to-speech models across reasoning, conversation quality, task completion, and speed.
| Measurement | Grok Voice Think Fast 2.0 |
| Speech-to-Speech Quality Index | 82.9% |
| Speech Reasoning | 97.2% |
| Conversational Dynamics | 95.1% |
| Agentic Performance | 56.5% |
| Time to First Audio | 0.70 seconds |
The results show strong reasoning and conversational timing. However, the 56.5% Agentic Performance score suggests that voice models can still struggle with some connected tasks.
A system may sound natural while still selecting the wrong appointment, misunderstanding an order number, or updating the wrong record.
Can Grok Voice Handle Interruptions?
Grok Voice is designed to manage interruptions, corrections, and changes during a conversation.
A caller might say:
“Book the 3 p.m. appointment—actually, make it anything after 4.”
The system should recognize that the second instruction replaces the first.
The earlier Think Fast 1.0 model was built for calls involving noise, accents, interruptions, and frequent tool use.3 Think Fast 2.0 continues that approach with updated speed and transcription performance.
How Much Does Grok Voice Cost?
Grok Voice Think Fast 2.0 costs $0.08 per minute of audio.
| Usage | Estimated Model Cost |
| One 5-minute call | $0.40 |
| One 10-minute call | $0.80 |
| 1,000 five-minute calls | $400 |
These figures cover the model only. Businesses may also pay for telephone service, storage, software connections, security, monitoring, and human support.
xAI previously listed an additional telephony cost of $0.01 per minute for numbers provided through its Voice Agent Builder. Companies should confirm current pricing before setting a budget.4
What Is the Grok Voice Agent Builder?
The Grok Voice Agent Builder is xAI’s no-code tool for creating business voice agents.
Businesses can choose a voice, provide instructions, upload company information, connect outside tools, and set rules for when a call should be transferred.
xAI also introduced 21 additional flagship voices in July 2026, along with updated versions of its original voices.5
A simple information line may be easy to set up. Services that handle payments, health information, or account changes will need stronger security and more testing.
What Should Businesses Watch For?
Before using Grok Voice, companies should review:
1. Whether the system understands real customers
2. Whether it completes the correct action
3. How private information is stored
4. When identity checks are required
5. How callers reach a person
6. Whether callers are told they are speaking with an automated system
A natural voice is not enough. The system also needs to be accurate, secure, and easy to leave when a caller needs human help.
Frequently Asked Questions
What is Grok Voice?
Grok Voice is xAI’s technology for spoken AI interactions. It can listen to callers, respond with speech, and use connected tools to complete approved tasks.
How fast is Grok Voice Think Fast 2.0?
It recorded a 0.70-second time to first audio in Artificial Analysis testing. Actual performance may vary during live calls.
How much does Grok Voice cost?
The published price is $0.08 per minute of audio. Phone service and other operating costs may be added.
Can Grok Voice replace customer-service employees?
It may handle routine calls, but businesses should keep human support available for disputes, sensitive requests, unusual problems, and failed transactions.
Citations
- xAI. “Introducing Grok Voice Think Fast 2.0.” SpaceXAI, 29 July 2026.
- Artificial Analysis. “Speech to Speech Models and Providers Analysis.” Artificial Analysis, 2026.
- xAI. “Grok Voice Think Fast 1.0.” SpaceXAI, 23 Apr. 2026.
- xAI. “Introducing the Voice Agent Builder.” SpaceXAI, 1 July 2026.
- xAI. “21 New Flagship Grok Voices.” SpaceXAI, 6 July 2026.
