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POST
cURL
This does not unsend a message. If the send is already in flight, it may still go out. Messages whose delivery is already confirmed return 400.
Repeat calls are idempotent — cancelling the same msg_id again still returns cancelled: true.

Authorizations

Authorization
string
header
required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Path Parameters

msg_id
string
required

Contiguity message ID (text_… or imsg_…), the same id returned when the message was sent.

Example:

"text_u98sZQCVsLvgBq80"

Response

Cancel a queued SMS, iMessage, or fast-track send. Does not unsend a message already in flight. If the message was recently retried, cancellation applies when it becomes up for retry again (up to about an hour). Idempotent.

id
string
required
Example:

"req_xxxxxxxxxxxxxxxx"

timestamp
number
required
Example:

1787072276500

api_version
string
required
Example:

"v2026.8.18"

object
string
required
Example:

"response"

data
object
required