베스트 답변
Send them a WhatsApp link from inside the Instagram DM, with a prefilled message, so the thread opens on their side with the context already in it.
The handoff step does this: it builds the link to your WhatsApp number, attaches a prefilled first message, and the tap opens WhatsApp with that text ready to send. When they send it, your WhatsApp automation picks up the conversation and can read the code in the message to know who they are and where they came from.
Why bother rather than just pasting a number:
- A number has to be copied, saved and searched. A link is one tap.
- The prefilled message is how the two conversations get joined. Without it the WhatsApp side starts with a stranger saying "hi".
- WhatsApp conversations behave differently from Instagram ones, which is usually the reason to move in the first place.
Two things to decide. WhatsApp charges per conversation while Instagram does not, so the handoff should happen when the conversation is worth it, not on every first message. And the person has to actually have WhatsApp, so keep the Instagram branch working for people who do not tap.
The Instagram to WhatsApp flow is the built version with the prefilled code already wired, which is the fiddly part to build from scratch.