RCS Business Messaging

RCS Business Messaging lets your agent text as a branded sender — your name and logo on the thread instead of a bare phone number — with delivery and read receipts, and tappable quick-reply chips. It runs through the same POST /v1/messages endpoint as every other channel.

RCS is concierge-onboarded. Carriers approve each brand individually, so there is no self-serve signup yet. Reach out to founders@agentphone.to and we set up your RCS agent, run the carrier launch process with you, and place the line on your account.

Your RCS line

An RCS agent arrives on your account as a line whose address starts with rcs_ (for example rcs_acme) instead of a phone number. It behaves like any other number: attach it to an agent, see its threads in Conversations, receive inbound through the same webhooks.

Sending

Address RCS explicitly — use your rcs_ address as from_number, or pass channel: "rcs":

curl -X POST https://api.agentphone.ai/v1/messages \
  -H "Authorization: Bearer $AGENTPHONE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from_number": "rcs_acme",
    "to_number": "+13105550123",
    "channel": "rcs",
    "body": "Your order has shipped! Want delivery updates?",
    "buttons": ["Yes, keep me posted", "No thanks"]
  }'

Sends that pass only agent_id go out as SMS from one of the agent’s phone numbers — the platform never silently promotes a send to RCS. If you want RCS, say so.

buttons become tappable quick-reply chips (up to 11 per message, 25 characters each). A tap comes back as a normal inbound message carrying the chip’s text.

SMS fallback

Not every handset can receive RCS. If your line has an SMS fallback number configured (we set this up with you during onboarding), a send to a non-RCS handset is delivered automatically as a plain text from that number — same API call, nothing to detect on your side.

The message’s channel always reflects what you asked for (rcs); when delivery actually happened over SMS, the message carries deliveredChannel: "sms" so downgrades are never invisible. In the dashboard those messages show “Delivered as SMS”.

The fallback number is a real number on your account: replies to it reach the same agent, and it can’t be released while it’s serving as a fallback.

Opt-outs — what you must send yourself

When a recipient replies STOP (or STOPALL, UNSUBSCRIBE, CANCEL, END, QUIT), AgentPhone records the opt-out and blocks further sends to them from your RCS agent — subsequent sends return a clear 403. A reply of START opts them back in.

AgentPhone never sends messages on your behalf, so your agent or backend must send the opt-out confirmation text itself (the STOP response you provided during carrier onboarding). The same applies to HELP responses. One confirmation message is allowed after a STOP; anything further is blocked until the recipient opts back in.

Billing

RCS messages bill per message from your credits, inbound and outbound, at the RCS rates shown on your Billing page (the RCS tab in transaction history). A message that falls back to SMS bills at the rate of the send you requested.