The process of integrating WhatsApp Business API with a Twilio account is more complex for Independent Software Vendors (ISVs) and System Integrators (SIs) than for individual businesses. To set up WhatsApp integration, ISVs need to configure their Twilio accounts, create subaccounts if necessary, prepare a valid Meta Business Manager ID, request access to WhatsApp, sign legal documents, purchase a Twilio phone number, create a WhatsApp sender, and optionally apply for an Official Business Account or use the Content API. Each step requires careful consideration of regulatory compliance requirements and approval by WhatsApp. With these steps completed, ISVs can send WhatsApp messages from their Twilio account using pre-approved templates.