> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/nfc-wallet-sdk-android/help/faq.md). # FAQ Quick answers to common **NFC Wallet SDK** questions. ### What is replenishment? In a HCE solution like NFC Wallet, payment credentials have a limited lifetime. Replenishment refreshes these credentials before or after they expire. For implementation details, see [Replenish payment keys](/nfc-wallet-sdk-android/implement-nfc-wallet/make-payment/replenish-payment-keys.md). ### How many transactions are returned by the transaction history server? Transaction history limits depend on the payment network: * Time window (for example, transactions from the last 30 days). * Maximum count (for example, the last 10 transactions). ### Which obfuscation tool is used? DexGuard. ### Does the Issuer need to implement both green and yellow flows in the first release? No. It's depends on your NFC program You can ship the **green flow** first. You can add the **yellow flow** (step-up authentication) in a later release if required by your program. ### Who generates the OTP in the ID\&V flow? The **TSP** generates the OTP and then issuer backend is responsible to send this OTP to the end user. ### Is there a limit to the number of cards to be tokenized per digital wallet application? No, there is no limit. ### What is a digital card ID? It is the unique identifier for a digitized card. The Thales platform generates it. See [Digital card id versus tokenized card id](/nfc-wallet-sdk-android/implement-nfc-wallet/manage-digital-cards/display-digital-cards.md#tokenized-card-id-versus-digital-card-id) ### How do I retrieve the correlation ID for digitization failures? Read the correlation ID from `MobileGatewayError.getCorrelationId()` or `ProvisioningServiceError.getCorrelationId()` when an eligibility or digitization step fails. After a successful eligibility check, you can also read it from `TermsAndConditions.getCorrelationId()` and store it for later troubleshooting. Share the correlation ID when investigating an issue with Thales support. For examples and implementation details, see [Use correlation ID](/nfc-wallet-sdk-android/additional-features/use-correlationid.md). ### What is a product ID? It identifies the card product (for example, Platinum or Gold). ### How do we avoid showing terms and conditions (T\&C) again? Use the SDK method to record T\&C acceptance on behalf of the end user. Do not prompt again unless your program requires it (for example, T\&C version changes). ### When sending card information, what fields are required? At minimum, send the **FPAN** and expiry date. Depending on your program, you might also need the **CSC** (CVV2). ### When requesting a token from Mastercard or Visa, is CSC (CVV2) required? It depends on your program configuration and risk requirements. If required, send **CSC** (CVV2) from the end user’s card entry flow. ### Do the Thales NFC Wallet SDK methods call the TSP and card issuer APIs directly? No. The **NFC Wallet SDK** calls Thales backend APIs. Then Thales **NFC Wallet backend** is responsible to call the required TSP API or card issuer API. ### Is it possible to "terminate" or "freeze" a card through the Thales NFC Wallet SDK? Yes. See [Delete a digital card](/nfc-wallet-sdk-android/implement-nfc-wallet/manage-digital-cards/manage-digital-card-lcm.md#delete-a-digital-card). After deletion the application removes the card from device storage. See [Suspend a digital card](/nfc-wallet-sdk-android/implement-nfc-wallet/manage-digital-cards/manage-digital-card-lcm.md#suspend-a-digital-card) to suspend a card, but many programs do not allow end-user self-service suspension. If you need to block payments from the application side, you can also unset the default payment card (see [Default card management](/nfc-wallet-sdk-android/implement-nfc-wallet/manage-digital-cards/set-the-default-payment-card.md#digitalizedcardmanager-for-default-card-management)) ### Is there any other push platform supported other than FCM? Yes. You can use **HMS Push Kit** on Huawei devices. You can also integrate your own push messaging platform, based on Thales specifications. For setup details, see [Configure push provider](/nfc-wallet-sdk-android/get-started/configuration/5.-push-notifications/configure-push-provider.md). ### Are push messages mandatory in order for the SDK to work as expected? Yes. Push notifications are required. Several NFC Wallet SDK operations rely on them (for example, Tokenization, LCM updates, and replenishment). --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.payments.thalescloud.io/nfc-wallet-sdk-android/help/faq.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. 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