# Backchannel Authentication User Notification Service

> Documentation for the IBackchannelAuthenticationUserNotificationService interface which is used to notify users when a CIBA login request has been made.

#### Duende.IdentityServer.Services.IBackchannelAuthenticationUserNotificationService

[Section titled âDuende.IdentityServer.Services.IBackchannelAuthenticationUserNotificationServiceâ](#duendeidentityserverservicesibackchannelauthenticationusernotificationservice)

The `IBackchannelAuthenticationUserNotificationService` interface is used to contact users when a [CIBA](/identityserver/ui/ciba/) login request has been made. To use CIBA, you are expected to implement this interface and register it in the ASP.NET Core service provider.

## IBackchannelAuthenticationUserNotificationService APIs

[Section titled âIBackchannelAuthenticationUserNotificationService APIsâ](#ibackchannelauthenticationusernotificationservice-apis)

* **`SendLoginRequestAsync`**

  Sends a notification for the user to login via the [BackchannelUserLoginRequest](/identityserver/reference/models/ciba-login-request/) parameter.
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