Sell the conversation, not the message
A ~15-turn agent chat is one billed 24-hour session — not a stream of metered texts. The unit Google doesn't sell, manufactured for you.
open()send()close()
RCS just reached ~70% of US phones
The conversation layer
for AI agents.
Agent-native RCS messaging with automatic SMS fallback — one REST API, built to be driven by agents. We turn the carrier's 24-hour conversation into the runtime your agent lives in, and handle the 8–16-week compliance gauntlet underneath.
1B+RCS msgs / day in the US
3–7×more engaging than SMS
~10 minto first conversation
Built directly on Google RBM, with carrier-grade SMS fallback — abstracted into one agent-native surface.
RCS sender setup is self-service. Brand verification, carrier readiness and launch — over the API, or from your agent. No sales call to get a verified sender.
Not a messaging API. A conversation runtime.
Most messaging APIs sell a primitive, or raw reachability. Cadence sells the conversation — with compliance productized beneath it.
RCS-first, SMS-pragmatic
Rich cards, quick-reply chips, verified sender where RCS is reachable. Automatic, seamless SMS fallback where it isn't.
MCP-native
Drop-in tools for any agent framework. Your LLM lives inside the conversation — it doesn't manage messaging infrastructure.
Compliance, productized
The 8–16-week carrier gauntlet, opt-in vault, and STOP/HELP handling — abstracted into a status bar.
Trust & safety, by default
Verified-sender branding, a pre-disclosed fallback identity so a downgrade never reads as smishing, and PHI-safe-minimal templates enforced before anything reaches the wire.
verified_rcsbranded_smsPHI-safe
Three calls to a live conversation
Agent-initiated, opt-in enforced, fallback automatic, engagement measured.
01
Open
Your agent speaks first over RCS, with opt-in provenance and a PHI-safe template. Reachability and channel are resolved for you.
02
Converse
Consumer replies — chip taps and free text — arrive as typed events. Attach a flow and we answer them for you; register a webhook and we POST them to you.
03
Fall back & measure
Undeliverable? We flip to a branded SMS automatically and tell you it happened. Every leg is measured against your SMS baseline.
First conversation in ten minutes.
One POST with a sandbox key opens an agent-initiated conversation. Rich content auto-degrades to text on the SMS leg, and the channel flip arrives as an event rather than as a surprise.
- Plain REST — nothing to install, and an OpenAPI spec with real schemas
- Sandbox test devices — real RCS, no carrier-launch wait
- Free to build; $250 a month per brand to go live. The price is on this page.
agent.ts
// Attach a `flow` and Cadence answers every reply itself —
// no process of yours has to be running.
await fetch("https://api.cadencercs.com/v1/conversations", {
method: "POST",
headers: {
authorization: `Bearer ${process.env.CADENCE_KEY}`,
"content-type": "application/json",
},
body: JSON.stringify({
to: "+12025550123", agentId, brandId,
useCase: "transactional",
optin: { method: "appointment_booking", capturedAt },
flow: {
id: "confirm", name: "Appointment",
disclaimer: "Msg & data rates may apply. Reply STOP to opt out.",
steps: [{
id: "confirm",
text: "Your 3pm is confirmed. Reschedule?",
suggestions: ["Reschedule", "Cancel appt", "All good"],
smsFallbackText: "Your 3pm is confirmed. Reply 1 reschedule, 2 cancel, 3 all good.",
}],
closing: "Thanks — see you then.",
},
}),
});Free to build. $250 a month per brand to go live.
Saying “contact us” without a number is how a no-sales-call product acquires a sales call, so here it is.
Free
Build and test
The full sandbox, plus real RCS messages to your own phone. Nothing billed, no time limit.
Paid
$250 / brand / month
Includes one agent ($100/month for each additional agent) and carrier launch, so you can reach anyone. Monthly, quarterly or annual.
Waived
Registration & carrier fees
Brand registration, vetting and carrier provisioning are on us. The carrier gauntlet is the part we exist to absorb.
Usage on paid brands: RCS is 10¢ per conversation — one price for a 24-hour session and every turn inside it — and SMS fallback is 5.5¢ per message. An RCS conversation nobody replies to includes six messages, then 5.5¢ per additional message. Carrier messaging fees pass through at cost. GET /v1/usage itemises your month per brand.
To upgrade a brand, email support@cadencercs.com.
The steepest curve in messaging
Apple turned RCS on. The channel inflected in the same window agents did.
0%US RCS reach, up from ~5% pre-iOS 18
0%of operator messaging revenue by 2029, from 3%
$0BA2P RCS revenue by 2029
0%global RCS traffic spike after iOS 18
Give your agents a voice consumers trust.
The conversation layer for the agent era — RCS-first, fallback-native, compliance-handled.