How to warm up a new WhatsApp number for a bot: what works

Warming up a WhatsApp number means giving a new account a gradual, two-way history before it carries an agent’s traffic. WhatsApp publishes no warm-up schedule, so every plan is community practice. What its own white paper does say is clear: a new account that bursts or messages strangers looks like spam. Warm-up lowers that risk. It does not remove it.

Sources are labeled. Official means WhatsApp’s own pages, read on 19 October 2026. Vendor means a hosted WhatsApp API provider’s help page. Reported means a GitHub issue. Only the first is WhatsApp speaking.

Why are new WhatsApp numbers fragile?

A new number has no history, and WhatsApp says it judges accounts partly on history. In its 2019 white paper, “Stopping Abuse: How WhatsApp Fights Bulk Messaging and Automated Behavior” (linked from How to use WhatsApp responsibly), WhatsApp gives two examples. An account that registered five minutes earlier and tries to send 100 messages in 15 seconds is almost certainly abusive and is banned automatically. A new account that messages dozens of people who do not have it saved is judged against its history, including how suspicious its registration looked, because that could be spam or a person announcing a new number.

The same paper says anyone who gets a first message from an unknown number is offered “report” and “block” at once, and that reports of that first message are trusted more. For a new number, the riskiest thing it can do is start a chat with a stranger.

What does WhatsApp itself say about warming up?

WhatsApp’s own pages say nothing about warming up. The ones we read for this article give no schedule, number of days or message count: the responsible-use page, the ban and restriction pages, the unofficial-apps page and the Terms. What they do say points one way:

• Message only people who contacted you first or asked you to (responsible-use page).
• A restriction can follow “signs of engaging in spam, automated, or bulk messaging”, and it blocks new chats while existing ones keep working (About restricted accounts).
• Sudden volume from a new account is the white paper’s clearest abuse example.

Our reading: for a bot, the lowest-risk start is the pattern WhatsApp describes as normal. People write to the number, it answers, and the number of new people grows slowly.

What do vendors and builders recommend?

Vendors publish day-by-day plans. The most detailed we found is from Whapi, a hosted unofficial API. Its page was marked “last updated 2 years ago” when we read it, so it is dated, and the company offers its customers a warm-up tool (Whapi: warming up new numbers).

Its starter limits are no more than 2 messages per minute and 6 hours of activity per day. Its claim that older numbers resist bans better is a vendor claim, and nothing official backs it.

WAHA’s guide to avoiding blocks gives two rules that fit an agent: never start a conversation, and wait a random 30 to 60 seconds between messages (WAHA: how to avoid blocking). It also describes a “points system” where conversations earn points and spam tags and blocks cost them. That is WAHA’s mental model. WhatsApp has not published it, and nothing official backs the guide’s figure of 5 to 10 spam tags getting you banned.

A Baileys user suggested leaving a new number idle for two days, texting it from another number, then connecting the bot (Baileys #2131). That is one anecdote, not a finding.

What does not work, or has no evidence?

Four common warm-up ideas have no verified record, and some have reported failures.

• Random delays on cold messages. A whatsapp-web.js user used 20 to 35 second random delays, pauses every 25 messages, about 110 messages a day, appointment confirmations and a polite “please save my contact” message. The reporter still got a 24-hour restriction after about three messages to first-time contacts, and listed the number’s age among the suspects (whatsapp-web.js #4008).
• Chats between your own numbers. An Evolution API user built a flow in which his numbers chatted with each other before sending, and reported a ban during the warm-up (Evolution API #1870). One report proves little, but this is automated messaging among linked accounts, which the Terms and the white paper both treat as suspect.
• A longer warm-up when linking is the trigger. In WAHA #2223, a user reported two accounts restricted after linking with almost no sending, and a commenter said an account active since 2016 was restricted just by pairing. If linking itself causes the problem, no schedule fixes it.
• Warm-up tools. Vendors offer them. We found no independent measurement showing that any of them protects a number.

Nobody outside WhatsApp knows when a number stops counting as new. WhatsApp says it weighs hundreds of factors, so any fixed number of days is a guess.

How do you ramp an agent number?

An agent whose users write first starts ahead: every chat is one WhatsApp would call normal. Your lever is how many new people you send to the number each day.

1. Prepare the profile first. Set a real name, about text and photo before any traffic. WAHA’s guide says a number with no picture, name or status is more likely to be tagged as spam by hand.
2. Start with people who know you. Your team and friends write first, and you answer. Do not publish the link to everyone.
3. Cap new chats per day, and raise the cap slowly. The function below follows the upper end of Whapi’s published ranges for the first three days. The daily step after that is your decision, because the vendor gives no number.
4. Keep replies short. One to three messages per user message. Our reading: long bursts per user look less like a person.
5. Keep the number on one phone and one IP. Moving it around adds a variable. Do not relink a session that is working.
6. Stop adding users at the first warning. If sends to new contacts start failing, as with error 463, or WhatsApp shows a restriction notice, wait. WhatsApp says a restriction ends by itself.

// Daily cap on NEW chats for a young number. Days 0 to 2 follow the upper end of
// Whapi's published ranges; the step after that is your own choice.
export function newChatCap(ageDays: number, stepPerDay = 5): number {
  if (ageDays < 1) return 2; // day 0: people you know
  if (ageDays < 2) return 6; // day 1: 3 to 6 chats
  if (ageDays < 3) return 15; // day 2: 10 to 15 chats
  return 15 + (ageDays - 2) * stepPerDay; // day 3 on: gradually more
}

// Show your wa.me link to a new user only while today's budget lasts.
export function canInviteNewUser(ageDays: number, newChatsToday: number): boolean {
  return newChatsToday < newChatCap(Math.floor(ageDays));
}

Count ageDays from the day you first used the number, and newChatsToday as people who wrote for the first time today. Past the cap, show a waitlist message instead of the link. With the default step the caps are 2, 6 and 15 on days 0 to 2, then 20 on day 3, 25 on day 4, 40 on day 7 and 75 on day 14. These are an example schedule, not a level WhatsApp calls safe.

Log four numbers every day: new chats, messages sent, failed sends and any WhatsApp notice. A rise in failed sends to new contacts is usually the first sign of trouble, so lower the cap when you see one.

How does whasp warm numbers?

whasp warms numbers before you get them, so a new number starts like a person, and replacement numbers are warmed the same way. A number is usually ready at once, otherwise it takes about 30 minutes of setup (provisioning). You never run the ramp yourself.

Three built-in rules do the rest. Users always write first, so a number cannot open a chat cold (409 chat_not_open). Each number has caps: 100 active chats in 30 days, 40 new chats in 24 hours and 1,500 sent messages in 24 hours. And a number whose usage passes 80% of a limit turns at_risk in its health status, so you add a number before it fills. Warm-up lowers the risk and does not remove it. If a number is banned anyway, whasp replaces it at no cost and your users write to the new one (what to do when a number is banned).

What to do next

If you run your own numbers, apply the ramp and read why WhatsApp bans numbers so you know the other triggers. Planning for volume? How many WhatsApp numbers does your AI agent need? works out the capacity per number. To skip the warm-up work, see /pricing.