xAI: Get a Free US Phone Number + Step-by-Step Guide to Building an AI Voice Agent (Prompts Included)

First, the most explosive part: Free +1 Number

• Each account gets a real US phone number
• No monthly fee for the number
• Pay-per-call: approx. $0.06/minute ($0.05 voice + $0.01 phone)
• Supports voice cloning, knowledge base uploads, and security rule settings
• Free test calls in the browser; charges only apply to real calls

This is xAI's Voice Agent Builder launched in July. It's still in Beta, but it's already functional.

Entry: https://x.ai/voice (US node required!)

Step 1: Click Try It Free

Step 2: Create a Team

Step 3: Set Up

Step 4: Recharge

Recharge immediately? Don't panic

Many people see "Add credits" and think they have to pay for the number.

No. The number is free, but calls are prepaid. If the balance is 0, the number cannot be activated.

I suggest recharging $5 first (enough for testing) and turning on Auto top-up to refill when the balance is low.

5-Minute Setup Process

Step 1: Login and Recharge

Log in with your X account and recharge $5 first.

Step 2: Create Agent + Write Prompt

Describe what your Agent should do in natural language—this is the most critical step.

Copy and modify this directly:

1You are Adrian's digital twin, responsible for answering all incoming calls.
2Personality: Professional, warm, concise, and organized.
3
4Call Flow:
51. Greet politely and introduce yourself.
62. Ask for the caller's purpose and identity.
73. Reply based on the knowledge base.
84. Record and summarize important matters in detail.
95. Ask if there are any other questions before ending.
10
11Sound natural like a human. For complex questions, say "Let me record that for you, and I'll have Adrian reply to you personally later."

Step 3: Upload Knowledge Base (Highly Recommended)

Upload your personal bio, cooperation terms, FAQs, etc. Supports PDF / Markdown / TXT. The more complete the knowledge base, the more reliable the AI.

Step 4: Voice + Security Rules

• Use built-in voices or clone your own voice (upload 1-2 minutes of audio).
• Set Guardrails: Prohibit revealing privacy, making price promises, etc.

Step 5: Deploy → Get Number

Save and deploy, then select "Provisioned by xAI" to get your free number. Done, you now have a real +1 number.

4 Truly Useful Use Cases

① Personal AI Assistant (Highly Recommended): For collaborations, interviews, or scheduling—the AI screens and records first, then summarizes important info for you. It's like a 24-hour secretary.

② Content Creation Experiment: Set up a dedicated number for "listener call-ins" and use real conversations for podcasts, short videos, or thread content. Real human-AI dialogue has much more reach than pure text.

③ Side Hustle Screening: For photography, design, or consulting—the AI clarifies needs and budget before transferring to you. This saves a massive amount of ineffective communication.

④ Simple Customer Service: Upload product info, and the AI answers common questions 24/7. Perfect for small teams or individual creators.

3 Ready-to-Use Prompt Templates

Template A: Personal Assistant

1You are Adrian Punk's digital twin, responsible for answering all incoming calls.
2Personality: Professional, warm, concise, and organized.
3
4Flow:
51. Greet politely and introduce yourself.
62. Ask for the caller's purpose and identity.
73. Reply based on the knowledge base.
84. Record and summarize important matters in detail.
95. Ask if there are any other questions before ending.
10
11Sound natural, not mechanical. For complex questions, say "I'll record this and have Adrian reply personally."

Template B: Listener Call-in

1You are a podcast AI receptionist, relaxed and fun yet professional.
2Tasks:
3- Record listener names and questions.
4- Summarize core viewpoints after brief interaction.
5- Guide valuable contributors to leave contact info.
6
7Sound friendly, like chatting with a friend.

Template C: Side Hustle Screening

1You are a professional consulting appointment assistant.
2Responsibilities:
31. Ask what they specifically want to consult about.
42. Understand budget and time requirements.
53. Determine if it fits the service scope.
64. If qualified, book the appointment and record a summary.
7
8Sound professional and polite; do not easily promise specific prices.

Notes

• The number is free; calls are charged per minute.
• Currently excellent at receiving calls, but outbound capabilities are average.
• SMS functionality is still being improved.
• Some regions may temporarily fail to get an auto-assigned number (normal for Beta).
• You can view call recordings and transcriptions in the Console.

Getting a free US number and setting up an AI receptionist in minutes has an extremely low barrier to entry.

For content creators, this isn't just a tool—it's new infrastructure for experiments, content, and even small businesses.

Recharge $5 and try Template A to get started quickly.

About the Author

@AdrianPunk115