--- title: "Connect Grok to a Phone Number: SIP, Twilio, Porting" description: "Connect Grok to a phone number three ways: an xAI number, a SIP trunk or Twilio. How to keep your number, what it costs, and a go-live checklist." url: https://skipcall.io/en/blog/connect-grok-to-a-phone-number language: en last_updated: 2026-11-03 --- [Ask Claude about this article](https://claude.ai/new?q=I'm%20reading%20%22How%20to%20Connect%20Grok%20to%20a%20Real%20Phone%20Number%22%20\(https%3A%2F%2Fskipcall.io%2Fen%2Fblog%2Fconnect-grok-to-a-phone-number\).%20Read%20the%20article%2C%20then%20answer%20my%20questions%20about%20it.) [Ask ChatGPT about this article](https://chatgpt.com/?q=I'm%20reading%20%22How%20to%20Connect%20Grok%20to%20a%20Real%20Phone%20Number%22%20\(https%3A%2F%2Fskipcall.io%2Fen%2Fblog%2Fconnect-grok-to-a-phone-number\).%20Read%20the%20article%2C%20then%20answer%20my%20questions%20about%20it.) LinkedIn X [Back to blog](https://skipcall.io/en/blog) Voice AI Published 3 November 2026 # How to Connect Grok to a Real Phone Number A Grok voice agent is useless until it answers a real phone number. Here is how an AI reaches the phone network, the three ways to wire Grok to a number (an xAI number, a SIP trunk or Twilio Media Streams), how to keep the number your customers already know, and a go-live checklist. Written for people who do not write code. 3 ways to put Grok on a phone line: a number from xAI, your own number over SIP, or a Twilio number bridged with Media Streams $0.09 per minute all-in with the number xAI provides in the Voice Agent Builder: $0.08 of conversation plus $0.01 for the number 8 kHz the audio quality of a phone line, which xAI's official example passes through in μ-law with no conversion You can connect Grok to a phone number in three ways: use the number the Voice Agent Builder gives you, point your existing number at the agent through a SIP trunk, or bridge a Twilio number to the Grok Voice Agent API with Media Streams. The first two need no code. The third needs a developer. This is the least glamorous part of a voice agent project, and the one that decides call quality, the caller ID your customers see and a good share of the bill. Below we explain how a call reaches an AI, compare the three routes side by side, show how to keep the number customers already know, and finish with a go-live checklist. It is part of our [guide to Grok and phone calls](https://skipcall.io/en/blog/grok-phone-calls-guide). $0.01 per minute for the xAI-provided number, the only connection fee xAI publishes Node.js the language of xAI's official voice-agent-phone example, which bridges a Twilio number to the API < 1 s Grok Voice 3.0 response time claimed by xAI, before the network adds its own delay ## Why does an AI need a bridge to answer the phone? When someone dials your number, the call travels the phone network that carriers have run for more than a century. Grok runs in a data center and only understands digital audio streams. Something has to sit in between. That something is a carrier that receives the call on your number, turns the caller’s voice into a digital stream, sends it to the AI, and plays the AI’s voice back to the caller, continuously, for the whole call. Three terms describe that bridge in every vendor’s documentation: - **SIP**: the protocol that carries phone calls over the internet. A **SIP trunk** is a virtual line from a carrier that your numbers are attached to. - **Media Streams**: Twilio’s feature that sends a call’s live audio to a server you choose. - **μ-law**: the audio encoding used on phone lines, sampled at 8 kHz, or 8,000 times per second. ## What are the three ways to connect Grok to a phone number? ![Three ways to connect Grok to a phone number, from the caller to Grok: A, a number provided by xAI, plus $0.01 per minute, a US number during the beta; B, a SIP trunk, to keep your number with carrier rates applying; C, Twilio Media Streams, for developers, using xAI's official Node example with 8 kHz μ-law audio and no conversion](https://skipcall.io/assets/infographies/grok/figures/en/trois-branchements.jpg) Three routes from caller to Grok: the xAI number to test quickly, SIP to keep your own number, Twilio when a developer owns the agent. **A. A number provided by xAI** The Voice Agent Builder gives each account a free number, billed at $0.01 per minute on top of conversation. Perfect for testing. During the beta it is a US number, according to Cobus Greyling. **B. A SIP trunk** The Builder connects over SIP to major telephony providers. Your number stays with your carrier, which forwards calls to the agent. This is the route for answering a number customers already know. **C. Twilio Media Streams** With the Grok Voice Agent API, a developer uses a Twilio number whose Media Streams feature sends call audio to a server that relays it to Grok. Most flexible, but you write and host code. ## Which route should you pick? | | A. xAI number | B. SIP trunk | C. Twilio Media Streams | | - | - | - | - | | **xAI product** | Voice Agent Builder | Voice Agent Builder | Voice Agent API | | **Code needed** | No | No | Yes, a small server | | **Keep your number** | No, a new number | Yes | Yes, if it is on Twilio | | **Local number outside the US** | No during the beta | Yes, if your carrier provides one | Depends on Twilio’s coverage | | **Connection cost** | $0.01 per minute | Your carrier’s plan | Twilio’s rates plus hosting | | **Best for** | Testing in an hour | Running in production | A custom-built agent | The deciding question is whether you have a developer. Without one, the Builder with its own number, then a SIP trunk for your real number, covers most needs. We go through what the Builder can do in our [Grok Voice Agent Builder review](https://skipcall.io/en/blog/grok-voice-agent-builder-review). With a developer, the API opens more options in exchange for a server to maintain. ## What happens on the line during a call? Here is the path of an inbound call when a Grok agent answers through a bridge like Twilio, the most common setup. 01 #### A customer dials your number instant The call crosses the regular phone network to the carrier hosting your number, a SIP provider or Twilio. 02 #### The carrier opens an audio stream a few hundred ms Instead of ringing a desk phone, the carrier opens a connection to your server and streams the call audio in the phone format, μ-law at 8 kHz. 03 #### Your server relays the audio to Grok continuous The server forwards that stream to xAI’s real-time API. In xAI’s example, the μ-law audio passes through unchanged: less processing, less delay. 04 #### Grok answers out loud under the claimed second The model listens, decides and streams its reply back, which your server hands to the carrier and the caller. The loop runs until the call ends. 05 #### Transfer or hang up per scenario The agent ends the call, or transfers it to a person when the request is beyond it. The transcript and summary are saved for follow-up. For the session mechanics on the AI side, including settings, events and per-minute billing, see our [Grok Voice Agent API guide](https://skipcall.io/en/blog/grok-voice-agent-api-guide). ## What is in xAI’s official Twilio example? xAI’s GitHub repository xai-cookbook includes an example called voice-agent-phone, also documented on xAI’s site. It is a small Node.js and TypeScript server built with Express and WebSockets, which keep a connection open for the whole call so audio can flow both ways. It links a Twilio number to Grok’s real-time API. Its most useful design choice is not in the code itself: audio stays in μ-law at 8 kHz, the phone network’s native format, from end to end. Every format conversion adds processing and therefore delay. Skipping it saves milliseconds on every exchange, and on a phone call, those milliseconds are what makes the agent sound quick or sluggish. > On a phone call, latency is paid twice: once while the AI thinks, once while the network carries the sound. The best model in the world sounds slow on a bad line. ## How much does the connection add to the bill? Grok’s conversation price, $0.08 per minute today, is only part of the invoice. The connection adds its own cost, which depends on the route: - **The xAI number** adds $0.01 per minute in the Voice Agent Builder, so $0.09 all-in. It is the only connection fee xAI publishes. - **A SIP trunk** is billed by your carrier: trunk subscription, number rental and minutes, depending on its plan. xAI publishes no SIP surcharge. - **A Twilio bridge** is billed by Twilio at its own rates for the number and minutes, plus hosting for the relay server. Do the math on your real call volume and average length. At a few hundred calls a month, the routes cost about the same. At several thousand, the carrier’s per-minute rate weighs as much as the AI’s. ## How do you keep the phone number your customers know? Changing numbers to deploy a voice agent is a bad trade. You have two situations: - **Your number is already on a SIP-capable carrier.** Configure the trunk to deliver calls to the agent. The Builder supports SIP to major telephony providers. - **Your number is with a provider that has no SIP option.** Port it to one that does. You keep the digits and change only the carrier. In the US, the FCC sets one business day for simple ports and four business days for others, and you will need a signed Letter of Authorization and an accurate Customer Service Record. Our guide to [business phone number porting](https://skipcall.io/en/blog/business-phone-number-porting) walks through the process and the mistakes that lose a number. If you need a new local or toll-free number rather than a ported one, our guide on [how to get a virtual phone number](https://skipcall.io/en/blog/how-to-get-a-virtual-phone-number) covers the options. ## What about outbound calls from an AI number? Answering calls with an AI and placing calls with one are not governed by the same rules. In February 2024, the FCC ruled that AI-generated voices are “artificial” voices under the TCPA, which brings the consent requirements for artificial-voice calls into play. A number that places unwanted automated calls can also get flagged as spam by carriers and call-blocking apps, which hurts every call you make from it afterward, as we explain in [why business numbers get marked as spam](https://skipcall.io/en/blog/caller-id-marked-spam). We cover what an AI can and cannot do on sales calls in [Grok vs. sales reps](https://skipcall.io/en/blog/grok-vs-sales-reps). ## How do you know the line will hold up? A voice agent already brings its own response time. If the bridge server, or the office connection your team uses when calls are transferred, adds latency, the conversation turns choppy and callers talk over the agent. **Latency** The round trip between the carrier, your server and the AI. Hosting the bridge close to both cuts the delay. **Packet loss** Chunks of audio lost on the way: the AI mishears, the caller hears gaps. Stability matters more than raw bandwidth. **The human handoff** When the agent transfers, your team picks up, often on a cloud phone system. Their connection has to hold up too. ## Go-live checklist Work through these in order before an AI answers a real number: 1. **Pick the route**, A, B or C, from the table above, and write down the resulting cost per minute. 2. **Test on a secondary number** or through evening forwarding, never straight on your main line. 3. **Check the caller ID** your callers will see, and whether it looks local to them. 4. **Measure the line**: latency, jitter and packet loss from where the bridge runs. 5. **Set up the transfer** to a person, and test what happens when nobody answers. 6. **Script the disclosure**: the agent says it is an AI and that the call is recorded, in its first sentence. 7. **Keep a rollback**: a forward to your usual phone system you can switch on in a minute. 8. **Port the number** only once the pilot works, with your LOA and CSR ready. In most setups the agent takes a slice of the calls and your team handles the rest. For them, business numbers on a reliable VoIP system remain the foundation. That is what Skipcall provides for sales teams, from $25 per month (billed annually), no commitment. ## The bottom line Connecting Grok to a real phone number means building a bridge between the phone network and the AI. Without a developer, the Voice Agent Builder gives you a test number, then connects over SIP so the agent can answer the number you already have. With a developer, xAI’s official example bridges a Twilio number to the API while keeping phone audio in its native format. Either way, keep your number by porting it, test the line and the handoff, and keep a rollback ready. For the full picture of xAI’s voice products, head back to our [Grok phone calls guide](https://skipcall.io/en/blog/grok-phone-calls-guide). _Sources: xAI, “Grok Voice Agent Builder” (July 1, 2026) and “Grok Voice 3” (October 14, 2026); xAI documentation, voice-agent-phone example; GitHub xai-org/xai-cookbook; Cobus Greyling, Builder analysis; FCC Declaratory Ruling FCC 24-17 (February 8, 2024)._ Author [Charles Baldet](https://skipcall.io/en/author/charles-baldet) [Charles Baldet on LinkedIn](https://www.linkedin.com/in/charlesbaldet/) CEO & Co-Founder, Skipcall Charles is the CEO and co-founder of Skipcall. A sales commando with over 10 years of experience in B2B SaaS and complex strategic accounts, he has closed major deals with Stellantis, SNCF, RATP and Natixis. A specialist in the PUCCKA and MEDDIC methodologies, Charles regularly teaches sales at HEC's incubator and the Sorbonne. He was ranked among Les Echos' top 10 business angels under 35 in 2020. He also co-founded Getalead (B2B sales agency) and Getlab (SalesTech studio). [See all their articles](https://skipcall.io/en/author/charles-baldet) ## A calendar full of meetings starts with a call. [Get started now](https://app.skipcall.io/signup) [Book a demo](https://skipcall.io/en/demo) **No commitment** · Number live in 2 minutes FAQ ## Frequently asked questions **Can an AI agent answer my existing business number?** Yes. The usual route is SIP: your number stays with a carrier that supports SIP trunking, and calls are forwarded to the agent. If your current provider does not offer SIP, you can port the number to one that does and keep the same digits. **What is a SIP trunk, in plain English?** SIP is the protocol that carries phone calls over the internet. A SIP trunk is a virtual phone line from a carrier: your numbers sit on it, and incoming calls can be delivered to whatever system you choose, a PBX, a softphone or an AI voice agent. **Why would I use Twilio instead of the Builder?** Twilio is a programmable carrier. Its Media Streams feature sends live call audio to a server you run, which can relay it to the Grok Voice Agent API. That gives a developer full control over the agent's logic, at the cost of writing and hosting code. xAI publishes an official example of exactly this setup. **Does the free xAI number work for calls outside the US?** During the beta, the number xAI provides is a US number, according to analyst Cobus Greyling. Callers in other countries can still dial it, but it will look foreign to them. For a local presence abroad, bring your own number over SIP. **How long does it take to move my number to a SIP carrier?** It depends on the port. In the US, the FCC sets one business day for simple ports and four business days for other ports, and most business ports are not simple. Plan the port only after your pilot works, and never cancel the old service before the port completes. **Do I need a developer to connect Grok to a phone number?** Not for the first two options. The Voice Agent Builder gives you a test number in minutes, and pointing your own number at it over SIP is a carrier setting. Only the Twilio Media Streams route requires code. Keep reading ## Related articles [View all articles](https://skipcall.io/en/blog) 01 Voice AI ### [Grok Voice Agent Builder Review: A No-Code Phone Agent](https://skipcall.io/en/blog/grok-voice-agent-builder-review) Since July 1, 2026, xAI's Grok Voice Agent Builder turns a plain-English brief, a few documents and a calendar into an AI agent that answers a phone number. We reviewed what it really does, what a month of calls costs, which calls it handles well, and why it is still a beta you should pilot rather than roll out. 3 Nov 2026 02 Voice AI ### [Grok Voice Agent API: How It Works and What It Costs](https://skipcall.io/en/blog/grok-voice-agent-api-guide) xAI's Grok Voice Agent API lets developers put Grok's real-time voice behind an app, a help line or a booking agent. Here is how a session actually works, what a minute costs in November 2026, how it compares with OpenAI's Realtime API, and the questions to settle before you ship it to production. 3 Nov 2026 03 Voice AI ### [How Grok Talks on the Phone: Voice AI, Explained](https://skipcall.io/en/blog/how-grok-talks-on-the-phone) Grok holds a phone conversation without the awkward pauses of older voice bots because one real-time model hears audio and speaks audio, with no detour through text. Here is how that works in plain English, why every AI voice still sounds like a phone call, which voices and languages Grok offers, and a five-minute test to judge any voice agent yourself. 3 Nov 2026 ## Ready to multiply your productivity? Join the sales teams that have transformed their prospecting. [Request a demo](https://skipcall.io/en/demo) Personalized demo • No commitment