Last updated 30 August 2026. Written while pricing a real US launch across three aggregators. No vendor's figures appear here — the structure is the same everywhere, and the structure is what surprises people.
SMS is cheaper and reaches everyone. RCS is richer, and proves who you are.
If your problem is cost or reach, use SMS. If your problem is that people do not trust or do not answer your messages, RCS is worth paying for. Most teams choose RCS for the wrong reason — they think it will be cheaper because it runs over data. It is not.
The surprise for anyone running surveys or check-ins is that RCS bills inbound messages. Rate cards quote a price "per MT/MO" — mobile-terminated and mobile-originated, meaning sent and received. On US SMS, inbound is usually free.
So if replies are your product, moving to RCS does not just add a premium per message. It starts charging you for the half of your traffic that used to cost nothing. A tap on a reply chip is a billable event. A carousel offering four chips per card is offering several.
RCS does have a cheaper mode, and it is worth understanding because it is unlike SMS entirely. Once a conversation reaches four messages within 24 hours, with at least two from the recipient, it triggers a session: one flat fee covers everything for the rest of the window. Twenty messages cost the same as four.
Which produces a genuinely strange result:
| Three-question survey | Messages | Session? | Relative cost |
|---|---|---|---|
| Answered fully | 6 | Yes | One session fee |
| Answered once, abandoned | 3 | No | Often more than the full one |
| Ignored | 1 | No | Per message |
Your worst-engaged conversations are your most expensive per conversation. If you model RCS costs on "messages per month" you will get a number that is wrong in the direction that hurts.
Every mobile phone receives SMS. RCS needs a compatible handset, the feature enabled, and a carrier that has launched your agent. Apple's adoption of RCS closed most of the gap on iPhone, but "most" is not "all", and coverage still varies by carrier and by how recently the device used RCS.
In practice this means you are not choosing between RCS and SMS. You are choosing RCS with SMS underneath, and the interesting question is what happens at the boundary.
Anything rich vanishes on SMS. Buttons have no equivalent. Cards have no equivalent. Carousels certainly do not.
So every rich message needs a text version, and the trap is that the two are usually written by hand and then drift. A booking carousel whose cards say Monday, Tuesday and Wednesday needs fallback text that numbers those same three days, in the same order. Change a card, forget the text, and a recipient on SMS replies "2" to a list that no longer matches — and both sides record it as a successful answer.
Three rules that prevent most of this:
This is what RCS actually sells, and it is the one thing SMS cannot do at any price.
A verified RCS sender shows your brand name, your logo, and a verification mark. Not a number. The recipient can see who is messaging them before they read a word.
SMS has no equivalent in the US. A ten-digit number is a ten-digit number, and the entire smishing industry runs on that fact. If your messages ask people to click, confirm, pay or reply with anything that matters, you are competing with fraud that looks exactly like you.
Which reframes the cost question. RCS is more expensive per message and more likely to be read, answered and believed. Whether that trade works is an arithmetic problem specific to your programme, and it turns on your response rate rather than your message volume.
US SMS needs 10DLC brand and campaign registration. Days, sometimes a week.
RCS needs all of that plus a verified RBM brand at Google, an agent, and separate launch approval from each carrier you want to reach. Google's brand review is quoted at around 15 days if nothing needs correcting. Carrier launch is separate and slower, and all three major US carriers manage their own approval — Google does not broker it for you.
Plan for weeks at minimum. A common and painful surprise is that domains younger than about 90 days are frequently auto-rejected, so a brand-new domain adds a wait nothing can shorten.
| If your problem is… | Use |
|---|---|
| Cost per message at volume | SMS |
| Reaching absolutely everyone | SMS |
| Shipping this week | SMS |
| People not trusting the sender | RCS |
| Low response rates on messages people asked for | RCS |
| Impersonation and smishing against your brand | RCS |
| Conversations rather than notifications | RCS |
For surveys, check-ins and reminders specifically: the honest answer is that RCS costs more and is worth it only if it lifts your completion rate enough to pay for itself — and because of session billing, a higher completion rate makes RCS cheaper per conversation as well as more effective. The two move together, which is unusual and worth knowing.
One number decides most of this: what fraction of your conversations get two or more replies?
That is the session trigger, and it is measurable from traffic you already send, including SMS traffic, because it describes human behaviour rather than a channel. Count conversations with four or more messages, at least one outbound and at least two inbound, inside a 24-hour window.
A programme at 70% has a very different bill from one at 20%, on the same rate card and the same volume. If nobody can tell you that number, nobody can tell you what RCS will cost.
One API and an MCP server for RCS with automatic SMS fallback. Brand onboarding, carrier readiness and the checks in this article are built in, so the failures above are reported rather than discovered.
Get a free sandbox key — no card, nothing to verify first — or read the agent-facing reference.
If you land on RCS: why your bill will not match your quote, the nine undocumented traps that get an agent rejected, and why approval alone still reaches nobody.