WhatsApp on iPhone: how to switch to a new phone number without losing anything? I have a long history of chats, several groups and multiple contacts (who have me in their address books) on Whatsapp for iPhone.

How can I preserve them all if I switch for a week to a new SIM card (which I buy for travel, from a different cell operator)? Is it possible to make the switch seamless for my friends, so they don't have even to add my new number (and of course, I'd like that their history of chats with me doesn't break on this switch)? After a week, I would like to switch back to my original SIM card -- and again don't want to loose anything. My iPhone device will remain the same all the time, and I'm not going to reset it during that period.

Whatsapp FAQ is quite unclear on this...
It proved trivial:


power down iPhone
change SIM card
turn iPhone on
launch Whatsapp
Whatsapp asks something like "Mobile network changed. Switch to new phone number?". Tap "No"


That's it. All groups, chat history and contacts preserved. My friends see me (and chat history with me) as I never changed SIM card or number.

Later switch back to the original number works exactly the same.

Mind the warning from Whatsapp FAQ: "Please do not swap SIM cards ... frequently, or you will create problems in the verification process." But with two changes "to new and back to the old" in half an hour, I of course didn't experience any problems.