
Mexico phone numbers in ACS only support inbound Toll-Free calls — no SMS, no outbound calls. So even if you get a number, it won't work for WhatsApp which needs two-way messaging.
The real reason numbers aren't showing up in Azure is your subscription billing address. Mexico numbers are only available if your Azure subscription is billed from: Australia, Canada, France, Germany, Italy, Japan, Spain, UK, or US. If you're billing from Mexico, nothing will appear.
Two options ,either use an Azure subscription billed from one of those countries, or email acstns@microsoft.com to request a case-by-case review.