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A brief note on the Inconsistencies for Mobile Numbers and their WhatsApp IDs in Brazil(digit '9') & Mexico(digit '1')

Understand the brief note on the inconsistencies for Mobile number and their WhatsApp Ids in Brazil and Mexico.

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Let us first understand what is a WhatsApp ID.

Numbers registered on the WhatsApp app is associated with a WhatsApp ID. Every WhatsApp account is tied to the phone number of the user and is called its WhatsApp ID. Usually, the WhatsApp ID of a number is the dialable format of the number itself. For example, the WhatsApp ID of the number "+1-225-555-1002" will be "+12255551002". But in Brazil and Mexico this is slightly different for some numbers.

Why do Brazil & Mexico phone numbers have differences between the actual dialable number provided by the operator and their WhatsApp IDs?

When WhatsApp was first installed on some people's phone they used an 8 digit number.  But Brazil and Mexico ran out of unique phone numbers and decided to add a an additional number to all 8 digit numbers. On December 10, 2010, ANATEL announced the inclusion of a ninth digit (in the format 9NNNN-NNNN) to mobile phone numbers.

The digit '9' was gradually added to the left of all existing mobile numbers in different regions of Brazil, regardless of their former initial digits. So, for example, mobile number +55 (11) 8765-4321 became +55 (11) 98765-4321.

Despite this fact, mobile phones registered outside the 11-19 (São Paulo), 21, 22, 24 (Rio de Janeiro), and 27-28 (Espírito Santo) areas are usually displayed on WhatsApp with the old 8-digit number, since WhatsApp IDs were already present for those numbers before the inclusion of the digit '9'.

Similarly, Mexico has also implemented the following changes in its dialing rules that affect WhatsApp users. When calling a Mexican cell phone from outside Mexico, the additional digit "1" after the country code is no longer required. Essentially, causing inconsistencies between phone numbers registered on WhatsApp and their actual WhatsApp IDs.

Impact on WhatsApp's Business APIs solution:

The problem is that WhatsApp has no way of knowing which numbers have been affected by this change. So on WhatsApp the ID of the number still remained as the old 8-digit numbers. When using the API, it creates the follwoing issues

Outbound message: Consider a user with phone number +55 (35) 98763-4321 who has opted-in to receive messages on WhatsApp. Using Zoko's send message API, the business sends messages to the user. And, with the help of inbound events, they determine that the message has failed to deliver, with "Number does not exist on WhatsApp" as the reason. However, the actual reason for this is because the WhatsApp ID of that number is +55 (35) 8763-4321, meaning without the digit '9'. It is unavoidable as the events are asynchronous.

Inbound message: Now, let us say the user initiates the conversation. From the inbound event, the business can determine the WhatsApp ID of the user. Using this, they can opt-in to that number as well and continue the conversation with the user.


There is no solution at the API provider level. We are waiting on WhatsApp to issue a fix (highly unlikely that this is coming)

Keywords: Whatsapp Number, Mexico, Brazil, Unable to send message, Add number.

A brief note on the Inconsistencies for Mobile Numbers and their WhatsApp IDs in Brazil(digit '9') & Mexico(digit '1')

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