I got a new phone number — what do I do?
In contrast to other messengers, your identity in Threema is not dependent on a phone number. Irrespective of the SIM card / phone number you're using or in which country you are, your Threema ID stays the same and everyone can still reach you. Your existing chats are unaffected by a change of your phone number as well.
Do you have a new phone number and don't want to use the old, linked one anymore? Simply delete the old number on the “My ID” tab and type in the new one — your ID is now linked to the right number.