SMS & Messaging platforms enable marketing teams to engage customers and prospects through outbound consumer-phone messaging channels — SMS, MMS, RCS, and WhatsApp Business. The category is unified by buyer (Lifecycle/Retention Marketing Manager) and job, even though channel choice varies by geography (SMS-dominant in US/UK; WhatsApp-dominant in EU/India/LATAM). Core capabilities include opt-in compliance (TCPA, CTIA, GDPR, WhatsApp Business policy), automated and broadcast campaigns, two-way conversation handling, abandoned-cart and post-purchase flows, link tracking, and integration with email/MAP/CEP. The market spans SMS-first platforms (Attentive, Postscript, Klaviyo SMS, EZ Texting, SimpleTexting, TextMagic) and WhatsApp Business platforms (ZOKO, GupShup, Wati).