WhatsApp has 2B+ users globally and dominates in LATAM, India, Southern Europe, and parts of Africa. Open rates exceed 95%. Far above any email channel.
Templated messages (HSMs) require Meta approval but can be sent to opted-in customers at any time. Conversational replies are free within 24 hours of the user's last message.
Callsy supports the WhatsApp Business API. Booking confirmations, payment reminders and cart-recovery follow-ups run over WhatsApp alongside voice, SMS, email, and WhatsApp, on one contact record. Supported channels: voice, SMS, email, WhatsApp.