A phone number in full international format includes a plus sign (+), then country code, city code, and local phone number. When contacting WhatsApp, always send your phone number in full international format.

For example, if a contact in the United States (country code '1') has the area code '408' and phone number 'XXX-XXXX', you'd enter +1 408 XXX XXXX.

Make sure to remove any leading 0s or special calling codes.

All phone numbers in Argentina (country code '54') should have a '9' between the country code and area code. The prefix '15' must be removed so the final number will have 13 digits total: +54 9 XXX XXX XXXX

Phone numbers in Mexico (country code '52') need to have '1' after '+52', even if they're Nextel numbers.