We optimise for clarity and speed: you should send a real message and see transparent billing before committing to any long-running vendor processes.

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Low friction to first value

Getting to a first working send should take minutes, not weeks.
Email is instant. Add a verified sender domain and send an action-based email with a single API call — no approval queue, no waiting period.
RCS has a sandbox. The Test Agent lets you send real RCS to your own device before your production agent is approved — rich cards, suggestions, and read receipts exactly as customers will see them.
Billing is visible from the first response. Every successful send returns a billing object with the hold amount, unit price, tier position, and remaining balance — no separate call needed.

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Errors you can act on

HTTP status codes map to actionable states:
CodeMeaningWhat you get
402Insufficient balanceCurrent balance, required amount, and a direct top-up URL
403Not authorised to sendReason (agent not approved, sender not verified, phone number mismatch)
429Rate limitretry_after hint
Opaque “forbidden” responses that give the client nothing to act on are not acceptable. Every error should tell you exactly what to fix.

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One API, multiple channels

The same POST /v1/messages endpoint handles email, RCS, and SMS (coming soon). The billing model, response shape, and webhook event structure are identical across channels — so adding a second channel to an existing integration is a configuration change, not a rewrite.

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Billing in every success response

Successful sends return billing metadata inline: holds, prices, tier context, balances. Your integration can display cost, check tier progress, and handle 402 without a separate API call. Continue to Errors and billing and the Billing API.