diff --git a/keyserver/addons/rust-node-addon/rust-binding-types.js b/keyserver/addons/rust-node-addon/rust-binding-types.js
index 3f3715d6a..671122fb9 100644
--- a/keyserver/addons/rust-node-addon/rust-binding-types.js
+++ b/keyserver/addons/rust-node-addon/rust-binding-types.js
@@ -1,27 +1,28 @@
 // @flow
 
 import type { SignedIdentityKeysBlob } from 'lib/types/crypto-types.js';
 
 type tunnelbrokerOnReceiveCallback = (
   err: Error | null,
   payload: string,
 ) => mixed;
 
 declare class TunnelbrokerClientClass {
   constructor(
     deviceId: string,
     onReceiveCallback: tunnelbrokerOnReceiveCallback,
   ): TunnelbrokerClientClass;
   publish(toDeviceId: string, payload: string): Promise<void>;
 }
 
 type RustNativeBindingAPI = {
   +registerUser: (
     username: string,
     password: string,
     signedIdentityKeysBlob: SignedIdentityKeysBlob,
   ) => Promise<boolean>,
+  +addReservedUsername: (message: string, signature: string) => Promise<void>,
   +TunnelbrokerClient: Class<TunnelbrokerClientClass>,
 };
 
 export type { RustNativeBindingAPI };
diff --git a/keyserver/addons/rust-node-addon/src/identity_client/add_reserved_username.rs b/keyserver/addons/rust-node-addon/src/identity_client/add_reserved_username.rs
new file mode 100644
index 000000000..8e6d6cfaa
--- /dev/null
+++ b/keyserver/addons/rust-node-addon/src/identity_client/add_reserved_username.rs
@@ -0,0 +1,23 @@
+use super::*;
+
+#[napi]
+#[instrument(skip_all)]
+pub async fn add_reserved_username(
+  message: String,
+  signature: String,
+) -> Result<()> {
+  // Set up the gRPC client that will be used to talk to the Identity service
+  let channel = get_identity_service_channel().await?;
+  let mut identity_client = IdentityClientServiceClient::new(channel);
+
+  let add_reserved_username_request =
+    AddReservedUsernameRequest { message, signature };
+
+  identity_client
+    .add_reserved_username(add_reserved_username_request)
+    .await
+    .map_err(|_| Error::from_status(Status::GenericFailure))?
+    .into_inner();
+
+  Ok(())
+}
diff --git a/keyserver/addons/rust-node-addon/src/identity_client/mod.rs b/keyserver/addons/rust-node-addon/src/identity_client/mod.rs
index 7c3cc3387..633c4ad24 100644
--- a/keyserver/addons/rust-node-addon/src/identity_client/mod.rs
+++ b/keyserver/addons/rust-node-addon/src/identity_client/mod.rs
@@ -1,61 +1,62 @@
+pub mod add_reserved_username;
 pub mod register_user;
 pub mod identity_client {
   tonic::include_proto!("identity.client");
 }
 
 use identity_client::identity_client_service_client::IdentityClientServiceClient;
 use identity_client::{
-  DeviceKeyUpload, IdentityKeyInfo, RegistrationFinishRequest,
-  RegistrationStartRequest,
+  AddReservedUsernameRequest, DeviceKeyUpload, IdentityKeyInfo,
+  RegistrationFinishRequest, RegistrationStartRequest,
 };
 use lazy_static::lazy_static;
 use napi::bindgen_prelude::*;
 use serde::{Deserialize, Serialize};
 use std::env::var;
 use tonic::{metadata::MetadataValue, transport::Channel, Request};
 use tracing::instrument;
 
 lazy_static! {
   static ref IDENTITY_SERVICE_CONFIG: IdentityServiceConfig = {
     let config_json_string =
       var("COMM_JSONCONFIG_secrets_identity_service_config");
     match config_json_string {
       Ok(json) => serde_json::from_str(&json).unwrap(),
       Err(_) => IdentityServiceConfig::default(),
     }
   };
 }
 
 #[derive(Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 struct IdentityServiceConfig {
   identity_socket_addr: String,
   identity_auth_token: String,
 }
 
 impl Default for IdentityServiceConfig {
   fn default() -> Self {
     Self {
       identity_socket_addr: "https://[::1]:50054".to_string(),
       identity_auth_token: "test".to_string(),
     }
   }
 }
 
 async fn get_identity_service_channel() -> Result<Channel> {
   Channel::from_static(&IDENTITY_SERVICE_CONFIG.identity_socket_addr)
     .connect()
     .await
     .map_err(|_| {
       Error::new(
         Status::GenericFailure,
         "Unable to connect to identity service".to_string(),
       )
     })
 }
 
 #[napi(object)]
 pub struct SignedIdentityKeysBlob {
   pub payload: String,
   pub signature: String,
 }