Rich Communication Services
RCS is replacing SMS for brand messaging, OTP, and consumer engagement. Every major US/EU carrier now supports RCS Universal Profile. If you build SMS communications today, you need to understand RCS UP for 2025+ deployments.
What It Defines
RCS is the carrier-grade upgrade to SMS/MMS: group messaging, read receipts, typing indicators, file transfer, rich media cards, and chatbots — all using IMS/SIP infrastructure. GSMA Universal Profile (UP) ensures cross-carrier interoperability. Apple added RCS support in iOS 18 (2024), enabling full Android-iOS interoperability.
Canonical (Normative)
Convenient (Practical)
Industry organization representing mobile operators worldwide. Publishes operational specifications including eSIM/eUICC (SGP.02, SGP.22), RCS Universal Profile, and network interoperability guidelines. Not a formal standards body but produces widely-adopted operator specifications.
Related Specs
SMS is how billions of people receive OTP codes, alerts, and notifications. Understanding PDU format, encoding (GSM-7 vs UCS-2), and concatenation is essential for any platform sending SMS at scale via Twilio, AWS SNS, or direct SMPP.
SIP is the PSTN of the internet. Every VoIP platform (Twilio, Vonage, AWS Chime, Asterisk, FreeSWITCH) speaks SIP. Building any communications product requires understanding INVITE flows, registration, and codec negotiation via SDP.
MMS is still widely used for group messaging (iMessage fallback on non-Apple devices), marketing images, and vCards. Understanding MM7 (application-to-MMSC API) is needed when integrating with carrier MMS gateways.