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.
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
- Usage-based, and the price is on this page. No sales call to ship.
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.",
},
}),
});Priced per conversation, not per message
One price covers a 24-hour session and every turn inside it. Saying “usage-based” without a number is how a no-sales-call product acquires a sales call, so here it is.
RCS
10¢ per conversation
Any number of turns within the 24-hour session. Same price in every market.
SMS
5.5¢ per message
The fallback leg, metered the way it is actually billed. No session rate exists for SMS anywhere, so charging per conversation would mean charging you for turns that may never happen.
—
Sandbox is free
Simulated delivery, real API. Build and test the whole loop before anything is billable.
An RCS conversation nobody replies to never opens a session, so it includes six messages and then bills 5.5¢ per additional message. SMS is per message from the first one. Carrier pass-through fees are billed separately, at cost. GET /v1/usage returns the same numbers for your own account, itemised.
Preview pricing. These are the rates we charge today and they are what the API bills, but they are provisional until real traffic shows the true turn distribution — we will give notice before changing them for anyone already sending.
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.