Toll-Free numbers that are Pending Verification or Verified and are blocked by the supplier for SPAM will receive Sinch error code 255.
Unverified TFNs that are blocked for SPAM will receive error code 64 (the same error received when exceeding TFN messaging limits)
Please see Toll-Free delivery report errors on the Sinch Developer site for a complete list of Toll-Free specific error codes.