A customer leaves a Russian phone number on a quote request. You see an 8 at the start, but WhatsApp expects an international number. Start by confirming the country: Russia uses +7, followed by ten national digits. The same country code is also used by Kazakhstan, so +7 alone does not identify the customer or their location.
For a saved contact, start with +, the country code and the complete national number. If you already have a number to check, open the WhatsApp number validator. Keep the original while you check the result.
Common WhatsApp country codes
| Country | Code and starting point |
|---|---|
| Russia | +7 and ten national digits |
| Kazakhstan | Also uses +7; confirm the full number |
| Mexico | +52; check WhatsApp's mobile-number guidance below |
| Argentina | +54, then the mobile 9 where applicable |
| Brazil | +55, the DDD area code and the national number |
The X characters in the examples below stand for digits. They are format examples, not telephone numbers to contact. A country code describes a numbering plan; it does not prove who owns an account.
Russia: country code +7, not the domestic 8
For a Russian number supplied in domestic form, replace the initial trunk prefix 8 with +7 and preserve the following ten digits. An illustrative conversion is 8 9XX XXX XX XX to +7 9XX XXX XX XX. Do not replace an 8 that appears inside the customer's number.
The ITU numbering plan for Russia and Kazakhstan confirms their shared +7 numbering zone and the Russian ten-digit national number. Check the remaining digits and the country supplied by the customer before assigning a country in your CRM. A prefix is not a reliable identity check.
Mexico: distinguish WhatsApp guidance from ordinary dialling
WhatsApp's international-number instructions say to include a 1 after +52 for Mexican numbers, giving a format such as +52 1 XX XXXX XXXX.
Ordinary international calling uses a different convention. The Mexican regulator's numbering tool shows +52 followed by a ten-digit national number, without that extra 1. Check which field you are filling: a contact, a telephone dialler and an integration's returned chat identifier serve different purposes.
Do not delete a leading 11 or other customer-supplied digits as a generic repair. Preserve the input, check the provider's expected format and inspect its response before changing an entire list.
Argentina: the mobile 9 and the domestic 15
WhatsApp's instructions say to put a 9 between Argentina's country code 54 and the area code, and remove the domestic mobile prefix 15. For a Buenos Aires mobile, a format example is +54 9 11 XXXX XXXX.
The area code matters: do not assume every Argentinian number has the same area-code length. If a customer supplies a local mobile number beginning with 15, ask for the area code and complete international number rather than treating 15 as a country code. Apply the transformation only after confirming that this is the Argentinian mobile case.
Brazil: check the DDD and the mobile ninth digit
A Brazilian mobile number contains +55, a two-digit DDD area code and a nine-digit mobile number starting with 9, for example +55 DD 9XXXX XXXX.
Anatel says the mobile ninth-digit migration was completed nationwide in 2017. An old list of selected DDD regions is not a suitable rule for current mobile numbers. If the supplied number already includes its ninth digit, do not insert another one. A fixed-line number needs its own check rather than a mobile-only transformation.
A contact, a wa.me link and an API field
You can display a saved contact with spaces for readability. A click-to-chat link uses the full international number in digits, without the +, spaces or brackets. WhatsApp documents this link format. The WhatsApp link generator helps you prepare the link and an optional message.
A value ending in @c.us is a chat identifier used in some integrations. It is not an email address or the phone-number field. Do not append it to a telephone number or construct it yourself. Follow the fields and returned identifiers in the Wassenger documentation.
Before updating a customer list
Work on a copy and keep separate columns for the original input, the confirmed country, the proposed number and the check result. This makes a correction reversible and lets a colleague see what changed.
- Choose one contact whose country and number you can confirm.
- Check the complete number, including its area code.
- Test the format in the validator before applying the same rule elsewhere.
- Review ambiguous entries separately instead of guessing their country.
For a quote request, asking the customer for the complete international number is often the fastest next step. A successful format check only answers whether the structure is plausible. Checking whether a WhatsApp account exists is a separate task, and neither result guarantees delivery of a later message.
Check one number in the Wassenger validator before changing the rest of your contacts.
