HSM (Highly Structured Message)
The original name for template messages on the WhatsApp Business API, still used in some legacy documentation and BSP interfaces.
How it works
HSM stands for Highly Structured Message, the original term Meta used for what are now called template messages. HSMs were the first mechanism for businesses to send outbound messages on WhatsApp, designed to prevent spam by requiring pre-approval of every message format. While Meta officially renamed HSMs to 'template messages' in 2020, the term persists in older API documentation, some BSP dashboards, and developer discussions. Functionally, HSMs and template messages are identical. Both refer to pre-approved message formats with variable placeholders that businesses use to initiate conversations outside the 24-hour window. If you encounter 'HSM' in documentation, treat it as synonymous with template message.
Related terms
Template Message
A pre-approved message format that businesses must use to initiate conversations with customers outside the 24-hour messaging window.
Business-Initiated Conversation
A conversation started by a business sending a template message to a customer, billed at a higher rate than user-initiated conversations.
BSP (Business Solution Provider)
A Meta-authorized partner company that provides businesses with access to the WhatsApp Business API along with tools, support, and compliance management.
Learn more in our docs
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