API Reference

Check RCS capability for phone numbers

post
https://api.transmitmessage.com/v2/rcs/capabilities

Synchronously checks whether a list of phone numbers can receive RCS from your sender.

Use this before sending to decide between RCS and SMS fallback. Designed for routing-time lookups: small batches (1–10 numbers recommended for best latency), immediate response.

Results are best-effort and reflect capability at the moment of the lookup. Do not use this as a hard gate on sending — treat UNKNOWN as reachable and rely on SMS fallback for hard delivery guarantees.

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Body Params

Request payload for the synchronous RCS capability check.

string
required

The RCS sender assigned to your account.

  • Example: DemoSender
phone_numbers
array of strings
required
length between 1 and 100

Phone numbers to check, in E.164 format without the leading +.

For best latency we recommend batches of 1–10. The endpoint accepts up to 100 numbers per request.

phone_numbers*
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Updated about 3 hours ago

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Updated about 3 hours ago