Tap once.
Bot Phone Line by CosVoice lands in your Grok Bot as your own copy. Rename it, change how it talks, keep it or delete it. Nothing you do to it reaches anyone else.
Grok Voice is a conversation between you and Grok. CosVoice is Grok on the phone with everyone else: a real number in your area code, calls in and out, its own email address, and a written summary of every call, back in the chat you already use.
Save the number as a contact. Call it from anywhere and you are talking to your Grok, out loud, with no app open. Text it an instruction and it does the job.
“Call the dentist and move Thursday to next week.” One sentence in Grok, and your Bot places the call, holds if it has to, and tells you what was agreed.
Forward your missed calls to it. It picks up as your assistant, takes the details, and the write-up is in your chat before you are out of the meeting.
Nothing to install. The tap adds a Bot to your own x.ai account that already knows the steps.
Bot Phone Line by CosVoice lands in your Grok Bot as your own copy. Rename it, change how it talks, keep it or delete it. Nothing you do to it reaches anyone else.
It connects CosVoice the way Grok Bot connects any tool: a page opens, you sign in, you press Allow. Then it asks your area code and the mobile you'll call from, shows the free numbers, and you pick one.
It answers as your line. After a call you get the write-up by email, and you can ask the Bot for it any time. After your first call, it offers to be woken the moment something happens.
Grok Bot has routines that can start on a webhook. CosVoice uses that. When a call ends, a text arrives at your line, or mail lands in its inbox, CosVoice starts your Bot itself, with the outcome and the transcript already in hand. If the call didn't get it done, the Bot works out the next step instead of waiting to be asked.
Your Bot offers to set this up after your first call. It takes ten seconds and it is optional: until then, every write-up arrives by email, so you miss nothing.
Grok Voice is you talking with Grok. xAI's Voice Agent Builder is a console for building a voice product of your own, and it is good at that: a free number, eighty-plus voices, cloning, a knowledge base, your own tools wired in. CosVoice is the third thing: the Grok Bot you already have, answering a real number today, with nothing to assemble.
| CosVoice | xAI Voice Agent Builder | |
|---|---|---|
| Works with the assistant you already have | Yes · Grok Bot, OpenAI dots, Claude, ChatGPT, Cursor | No · you build a new agent in the console |
| Ready without building anything | Yes · answer a few questions and it is live | Partly · a basic agent takes a couple of minutes to assemble |
| Wakes your own Bot when a call ends, a text arrives, or mail lands | Yes | No · the console notifies your team |
| The summary comes to you | Yes · your inbox and your Bot's chat, every call | Partly · recorded and transcribed in their console; sending it on is your job |
| Keeps the written call, not the audio | Yes · transcripts and notes only | No · every call is recorded |
| Says it is an assistant when asked | Yes · a rule of the product | Partly · a guardrail you write |
| Build your own voice product on it | No · one line, one assistant | Yes · many agents, your own tools and models |
Checked against xAI's own docs on 18 September 2026. The full comparison, every row, is at cosvoice.com/compare/xai. If you are building a voice product, use their builder; it is the better tool for that job.
Adding the Bot is free, and nothing is charged until you ask it for a number and pick a plan.
It says it is an assistant whenever anyone asks, and never claims to be a person. It will not read out a card number, agree to a charge, or commit your money. We keep the written call, never the audio, and call content is sealed to your line. How we hold the line.
Already have a Grok Bot you like? Don't start over: paste one address into the Bot you have and it gets the same line.
One tap, then about a minute. Free to add; ask it for a number when you're ready.
No. The line works on its own. Call it, text it, and ask it to make calls from your dashboard. If you do have a Grok Bot, or another assistant that supports MCP, connecting it lets your assistant make calls and read the summaries by itself.
No. Switch on Bot push and CosVoice wakes your Bot itself when something happens: you text the line an instruction, an email arrives, a call finishes. In Grok, make a routine with a Webhook trigger and paste its URL and key into Settings → Connect → Wake your Bot, or tell your Bot to set it up. From then on nothing waits for a check-in. It works with any assistant that has a webhook URL and a token.
It answers as your assistant in a natural voice and has a real conversation. It finds out who is calling and what they need, and writes down the amounts, dates, options, and next step. People you've approved get through warmly. Strangers get a polite assistant that never shares your details: your contacts and bookings are not part of a stranger's call at all. Numbers you block are turned away before the line answers. If a caller asks for something by email, the line can send one email per call, and only with links you put in its instructions.
Yes, whenever anyone asks. It introduces itself as your assistant and never claims to be you or a person. People are more helpful when they know.
On a call, no. It never gives out a card number or agrees to a charge, so a booking or appointment is the most it commits you to. Your plan's minutes are the only thing the line itself spends, and app orders (dinner, groceries) go through only after you confirm.
Starter is $29 a month with 100 minutes of calls. Plus is $79 with 300 minutes. Pro is $199 with 1,000. Extra minutes are $0.25 each, rounded up per call. Every plan includes the number, the email address, and the assistant connection.
Free for 7 days with 10 minutes of calls. Then $29 a month unless you cancel.