SMS can carry a verification code as part of an application’s authentication process when the business, message purpose, provider, route and destination support that use. Confirm the actual workflow with Blackleaf before planning an integration. Sending a code does not by itself prove a successful sign-in or prevent unauthorized access.
Confirm provider support before integration
A business license, customer request or sender registration does not establish that every verification message is permitted. For example, Twilio prohibits cannabis and CBD businesses from SMS and MMS in the United States and Canada, regardless of message content. This is a provider-specific example, not a determination of another route’s eligibility. A verification code is not an automatic exception; describe the business and purpose accurately.
Separate delivery from successful authentication
A message accepted for sending, a delivery report, a validated code and an application access decision are different events. Confirm which system owns each step and how pending, failed or expired attempts are handled. As a provider-specific illustration, Twilio documents a separate check of the user-provided verification token. This does not establish which verification features or integration your Blackleaf setup supports.
SMS also has authentication limitations. NIST’s authentication guidance describes telephone-network verification as restricted and explains that out-of-band authentication does not resist phishing. Review the channel and alternatives with the team responsible for your application’s security; a messaging service is one part of that decision.
Use Blackleaf’s application 2FA API
Blackleaf documents two dedicated operations in the current API reference: POST /messaging/send/2fa issues a challenge, and POST /messaging/verify/2fa checks a submitted code. Use workspace Bearer authentication from your backend. Send a JSON body with phone for issuance, then phone and code for verification in the same workspace and messaging environment. A text template is not required for this workflow.
Inspect the response body as well as the HTTP status. A verification request can return HTTP 200 with verified: false. On a match, correlate the returned sessionId with the intended application attempt. Your application owns the access decision and must prevent reuse of an already completed action. The documented check does not establish single-use code consumption or an attempt-limit policy. Keep live codes out of logs and support requests.
Use the sandbox 2FA walkthrough to rehearse issuance and verification without handset delivery. Try a matching code and a wrong code to check that your application keeps access blocked when the API returns verified: false. Sandbox issuance returns the generated test code; production does not. In a sandbox rehearsal, request a replacement code for the same phone and workspace. After successful issuance, confirm that your application accepts a match only for the replacement session. Pending challenges are temporary and must be checked by the API process that issued them; a restart clears them. Confirm request routing for your deployment. A matching sandbox code does not establish production readiness or authorize Blackleaf dashboard access.
Apply Blackleaf’s recipient requirements
Blackleaf requires explicit recipient consent and age confirmation before any text, including service and support messages. In the message flow, the intended recipient must select the birthday on file; never disclose the saved birthday. These are Blackleaf company requirements, separate from legal and provider-policy review. See the age and recipient verification guide.
The recipient check does not replace the application’s authentication process or establish provider approval. Requesting an account-verification code also does not create permission for recurring promotional texts. Keep the sender, purpose, permission and opt-out state appropriate to the actual program.
Bring one workflow for review
Prepare the facts needed to assess the proposed setup:
- Your business category, destination geography, message purpose and proposed provider or sending route.
- The consent, age and intended-recipient checks used in the message flow.
- The system responsible for code validation and access decisions, and what the user can do if SMS does not arrive.
- The statuses your team will monitor, the person responsible for unresolved attempts and the evidence needed to evaluate the workflow.
Discuss the proposed workflow with Blackleaf before activation. Explore Blackleaf’s Texting platform for the broader customer-messaging context, and keep account-verification communication separate from marketing enrollment.