RCS Messaging

RCS (Rich Communication Services) is the GSMA-standardized successor to SMS/MMS. It's IP-based, supports rich media up to 100 MB, branded sender display, suggested replies, carousels, and read receipts. Business-to-consumer RCS in the US is delivered through Google's RCS Business Messaging (RBM) platform. Apple shipped native RCS support in iOS 18 (released 2024-09).

RCS vs SMS/MMS — what's different

| Feature | SMS | MMS | RCS | |---|---|---|---| | Text length | 160 chars / segment | 160 chars + media | Up to 8,000 chars | | Media size | None | ~600 KB (carrier-dependent) | Up to 100 MB | | Sender display | Phone number | Phone number | Verified brand name + logo | | Read receipts | No | No | Yes | | Typing indicators | No | No | Yes | | Suggested replies | No | No | Yes (up to 11 chips) | | Carousels | No | No | Yes (up to 10 cards) | | Encryption | None | None | End-to-end (Google-to-Google) | | Carrier dependency | Universal | Universal | Carrier + device must support | | Fallback | None | None | Auto-falls back to SMS/MMS |

Where RCS works today (US)

Android devices with Google Messages app — RCS works carrier-side via Jibe (Google's hosted RCS platform). Coverage is universal across major US carriers as of 2023.
iOS 18+ — Apple added native RCS support. Works on all iPhones running iOS 18.0+ when paired with a carrier that has activated RCS for iPhone (T-Mobile, AT&T, Verizon all enabled by late 2024).
Older Android (no Google Messages) — RCS not available, falls back to SMS.
Older iOS (< 18) — Falls back to MMS for media, SMS for text.

For business messaging, assume 50-70% RCS reach in 2026 with rapid growth.

Two RCS flavors for business

Carrier RCS / Universal Profile

Person-to-person RCS, also accessible to businesses via specific carrier integrations. Limited business features, no branded sender. Rare in the US — Google's RBM is dominant.

Google RCS Business Messaging (RBM)

The dominant US business RCS channel. Verified by Google, supports branded sender, all rich features. Requires:

A verified Google Business Profile or registered RBM Agent
Brand verification through a Verified Sender process
Subscription to RBM via Google or a partner (Twilio, Sinch, Infobip, etc.)

SignalWire does not currently offer first-party RBM. Production RBM today goes through aggregators (Twilio, Sinch, Infobip). When SignalWire ships RBM, it will plug into the same SWML messaging APIs.

What an RBM message looks like

{
  "messageId": "msg-12345",
  "agent": "brands/acme-plumbing",
  "to": "+13105551234",
  "richCard": {
    "standaloneCard": {
      "cardOrientation": "VERTICAL",
      "thumbnailImageAlignment": "RIGHT",
      "cardContent": {
        "title": "Your appointment is confirmed",
        "description": "Acme Plumbing — Wednesday at 2 PM",
        "media": {
          "height": "MEDIUM",
          "contentInfo": {
            "fileUrl": "https://cdn.example.com/confirmation.jpg",
            "forceRefresh": false
          }
        },
        "suggestions": [
          { "reply": { "text": "Reschedule", "postbackData": "reschedule" } },
          { "reply": { "text": "Cancel", "postbackData": "cancel" } },
          { "action": { "text": "Call us", "postbackData": "call", "dialAction": { "phoneNumber": "+12125551111" } } }
        ]
      }
    }
  }
}

Suggestions render as tap chips below the message. Postback data fires a webhook to your backend when tapped, similar to a webhook from a button click in an interactive Messenger-style chat.

Brand verification for RBM

To send RCS as a verified business, the brand must pass Google's verification:

Register the business via Google Business Profile or an RBM partner.
Provide a logo (1024×1024 PNG), brand color, and short description.
Submit a sample message flow showing legitimate use case.
Add DNS-based domain verification on the brand's website.
Wait 3-10 business days for Google approval.

Verified brands get a checkmark icon, branded color in the chat header, and prominent logo. Unverified brands send as plain RCS without branding — still RCS-capable but visually similar to a regular SMS thread.

Apple RCS specifics

Apple's iOS 18 RCS implementation uses the Universal Profile 2.4 specification. Differences from Google RBM:

No native support for verified business sender branding (as of iOS 18.2)
Suggested replies render but with iOS-specific chip styling
End-to-end encryption uses Apple's PQ3 protocol (Google uses MLS)
Read receipts and typing indicators work cross-platform between iOS and Android RCS

iPhone-to-iPhone messages continue to prefer iMessage. RCS kicks in only when the recipient is Android-on-RCS or iMessage is unavailable.

Fallback behavior

Send to a number that doesn't support RCS and the message auto-falls back:

Text-only RCS → falls back to SMS
RCS with media → falls back to MMS
RCS with rich card → falls back to MMS with the title text + image
RCS with suggested replies → falls back to MMS, replies become inline text

This means never send RCS that depends on a tap-chip for the recipient to take action. Always include enough information in the text body for SMS-fallback recipients to understand and respond.

Cost model

RCS pricing through aggregators (typical 2025):

| Message type | Cost per message | |---|---| | Simple text RCS | $0.008 - $0.015 | | Rich card RCS (with media) | $0.015 - $0.025 | | Carousel RCS | $0.025 - $0.040 | | Inbound RCS (replies) | $0.005 - $0.010 |

More expensive than SMS but with higher engagement — RCS open rates run 75-90% vs 95% for SMS, but click-through is typically 5-10x higher on RCS.

When to choose RCS over SMS/MMS

| Use case | RCS | SMS/MMS | |---|---|---| | OTP / 2FA codes | No (latency, fallback delays) | Yes | | Appointment reminders | Yes (rich card with reschedule chip) | Yes (text + link) | | Marketing promos | Yes (carousel, branded) | Yes (text + image) | | Customer support replies | Yes (typing indicators feel chat-like) | Yes (works universally) | | Shipping notifications | Yes (carousel of items) | Yes (text + URL) | | Compliance-sensitive (financial, healthcare) | No (encryption story still maturing) | Yes (well-understood compliance posture) |

A2P 10DLC and RCS

RBM is separate from 10DLC. RCS messages do not flow through the 10DLC throughput pool — they have their own RBM throughput limits set by Google. However, the same opt-in/opt-out compliance applies under CTIA and TCPA. STOP/HELP keywords must be respected; opt-in records must be retained.

When RCS falls back to SMS/MMS, that fallback traffic does consume 10DLC throughput. Plan accordingly.

Common pitfalls

Sending rich content assuming RCS reach — always design for SMS fallback. Test by disabling RCS on a test phone.
Suggested replies as the only CTA — replies don't survive fallback. Include the CTA text in the message body.
No opt-in flow for RCS specifically — opt-in obtained for SMS does not automatically apply to RCS for compliance purposes. Treat RCS as a separate channel for consent records.
Mismatched brand verification across carriers — Google verification is one process. Aggregator verification may be additional.

Roadmap notes

2024-09: Apple iOS 18 ships RCS support
2024-Q4 to 2025-Q1: Major US carriers enable iPhone RCS interop
2025-2026: RBM Verified Sender expansion; carousel and form features mature
Future: SignalWire first-party RBM integration (no firm date as of 2026-05)

References

GSMA Universal Profile 2.4 — RCS specification
Google RCS Business Messaging — developer documentation
Apple iOS 18 release notes — RCS support
3GPP TS 26.114 — IMS multimedia telephony service

RCS Messaging — RBM, Google Business Messages, Apple RCS