What is the difference between coexistence and migrating to the API?
Coexistence keeps your number in the WhatsApp Business app and connects it to the WhatsApp Business Platform (the API) at the same time; migrating moves the number to the API alone. In both cases customers keep writing to the number they already know, and in both cases a platform like Rexenda can add a team inbox, AI agents and a CRM on top of it. The difference is what happens to the app on your phone: with coexistence it keeps working, and after a full migration that number no longer runs in the app.
That single difference drives everything else. Coexistence is Meta's way of letting small businesses grow into the API without giving up the phone they already answer from, the chats stored on it or the habits of the people who use it. A full migration treats the number as infrastructure: it lives only on the API, every message goes through the platform, and features the API supports but coexistence does not become available.
Neither option is better in the abstract. The right choice depends on who answers today, which features you need next and how much your chat history matters. The rest of this guide walks through each case, the rules Meta sets for each one and how to do it in Rexenda.
What do you keep, and what changes, with coexistence?
With coexistence you keep the app, the number and, if you choose, up to 180 days of chat history. When you connect, you can share the messages sent or received in the previous 180 days, so every customer arrives in Rexenda with context. Your contacts from the WhatsApp Business app sync too, and the messages you send from your phone afterward appear in the same Rexenda conversation, so your team and your AI agents see the whole exchange and nobody answers twice.
Meta also sets rules that are easy to miss. The history sync can be requested only once and only within 24 hours of connecting; after that, the number would have to be disconnected and connected again from scratch. You can also decline to share your history, which is a valid choice, not an error. You must open the WhatsApp Business app at least once every 14 days or Meta disconnects coexistence for that number, and the app can be linked to only one platform at a time. Meta requires app version 2.24.17 or later.
A few things change in the app itself. Broadcast lists are disabled, and disappearing messages, view-once messages and live location are turned off in one-to-one chats. Linked companion devices are unlinked when you connect; you can link them again, except WhatsApp for Windows and Wear OS. Messages you send from the app stay free, while messages sent through the API follow Meta's API pricing.
What doesn't work through the API when you use coexistence?
Group chats, voice and video calls and the app's business tools are not supported through the API on a coexistence number. Groups are not synced into Rexenda, and calls, catalogs, orders, status updates and your business profile stay in the app, where they keep working as before. If most of your sales happen in group chats or over WhatsApp calls, keep that in mind: Rexenda will show your one-to-one conversations, not those.
Throughput is the other limit. Meta fixes coexistence numbers at 20 messages per second. For a business that answers customers one by one, that is far more than enough; it only matters if you plan to send very large template campaigns from that number in short bursts.
These limits are the price of keeping the app, and for many businesses it is a good trade: the owner keeps answering from the phone while the team and the AI agents work from a shared inbox. When the limits start to hurt, that is usually the sign that a dedicated API number fits better.
When does migrating the number to the API make more sense?
Migrating makes more sense when the number has become a team channel rather than one person's phone, or when you need what coexistence cannot do through the API. A clear case is WhatsApp calls: on a number that lives only on the API, Rexenda's voice AI agent can answer WhatsApp calls, book appointments while the caller is on the line and leave a transcript and summary in the inbox. Another is volume: an API-only number is not tied to the 20-messages-per-second cap or to opening an app every 14 days.
The trade-off is the app. Meta does not allow a number already in use with WhatsApp to be registered on the API until it is deleted from the app, so the WhatsApp Business app stops working on that number and Rexenda becomes the place where you answer. Back up anything you want to keep first, because the history import is a coexistence feature. When you register, you also set a six-digit two-step verification PIN; keep it safe, because Meta asks for it to change the PIN or remove the number from the platform. Meta limits registration to 10 attempts per number in 72 hours, so have the PIN and access to the number ready before you start.
Many growing businesses use a mix: they keep their historical number in coexistence for the customers who already know it, and connect a second, API-only number for campaigns, calls or a new line of business. Depending on your plan, Rexenda handles several WhatsApp numbers in the same workspace, each with its own conversations and settings.
How do you connect either option in Rexenda?
In Rexenda both options start in the same place: create a free account, open the WhatsApp channel and launch Meta's Embedded Signup. Before Meta's window opens, you choose whether you are connecting the number you already use in the WhatsApp Business app or a number for the API only; nothing is preselected. If coexistence is available for your number, Meta's flow offers it and you confirm the link from the app on your phone. Coexistence is only available through Embedded Signup with a technology provider, which is exactly the route Rexenda uses.
For coexistence, decide about your history right away: you have 24 hours and a single attempt to import up to 180 days of chats. For an API-only number, have the six-digit PIN ready. In both cases Rexenda finishes the connection in the background, notifies you when the number is ready and shows the connection state of each number, so a disconnected or pending number never looks like a working one.
One cost note applies to both. Rexenda does not charge per WhatsApp message; Meta bills its message fees directly to your own Meta account. If you are unsure, start with coexistence: it keeps your app and your history, and you can add an API-only number later when calls, volume or team size call for it.