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Will I Be Charged If SIPSTACK Encounters an Error When Sending an SMS?

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Will I Be Charged If SIPSTACK Encounters an Error When Sending an SMS?

Section titled “Will I Be Charged If SIPSTACK Encounters an Error When Sending an SMS?”

SIPSTACK does not charge for a message if your API request returns an HTTP error, or if the message status is failed. SIPSTACK charges for messages where delivery was attempted, regardless of whether the message was ultimately received at the handset.

Message StatusCharged?Explanation
sentYesMessage left SIPSTACK and was passed to the carrier
deliveredYesCarrier confirmed delivery to the handset
undeliveredYesDelivery was attempted but failed at the carrier level
delivery unknownYesDelivery status could not be confirmed
failedNoMessage did not leave SIPSTACK

If your API request returns an HTTP error (e.g., HTTP 400), SIPSTACK was unable to process the request and no delivery was attempted. You will not be charged.

Common causes of API-level errors include:

  • Invalid or malformed To phone number (error 21211)
  • SMS geo-permissions not enabled for the destination country
  • Attempting to send to a recipient who has opted out (STOP)

A message with status failed did not leave SIPSTACK’s systems. You are not charged. Failed messages can result from:

  • Queue overflows
  • Account suspension
  • Media errors (for MMS messages)

In some cases, a message may leave SIPSTACK and be passed to a carrier, but never reach the end user’s handset — for example, if the carrier’s filtering system blocks delivery. These messages appear with status undelivered and are charged, because delivery was attempted.