Overview A single call sends on any messaging channel — SMS, MMS, RCS, or WhatsApp. The channel is determined by the sender address and the recipient's capabilities. For channel selection guidance and the full onboarding sequence, see and . | Channel | format | Notes | Template required? | |---------|-------------|-------|--------------------| | SMS/MMS | | MMS: US/CA/AU only | No | | RCS (with SMS fallback) | | Send via Messaging Service that has both an RCS sender and an SMS sender — Twilio attempts RCS first, falls back to SMS on failure | No | | RCS (no fallback) | | Forces RCS only — fai…