> 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/general/interfaces.md).

# SDK Communication channels

NFC Wallet uses dedicated communication channels between the NFC Wallet SDK running in the digital wallet application and the NFC Wallet backend.

NFC Wallet supports two communication channels, both fully managed by the product:

* **Wallet API** – APIs used by the NFC Wallet SDK for use cases such as:
  * SDK initialization with Wallet Secure Enrollment
  * Card enrollment initiation
  * Transaction history retrieval
* **Secure channel** – A secure communication channel used to provision sensitive assets, such as the digital card profile and payment keys.

To support use cases such as digital card life cycle management (LCM) events initiated by the issuer backend or the TSP, and transaction notifications, NFC Wallet also requires silent push notifications.

The NFC Wallet backend uses [Firebase Cloud Messaging (FCM)](https://firebase.google.com/docs/cloud-messaging) to send push notifications to the digital wallet application.

The diagram below illustrates the communication channels supported by NFC Wallet:

<figure><img src="/files/OtBhTKpbeVhnyWUl1B8E" alt=""><figcaption><p>Communication channels overview</p></figcaption></figure>

> If Firebase Cloud Messaging cannot be used, the digital wallet backend must support the Thales Wallet Push Server API.


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