diff --git a/Package.swift b/Package.swift
index b449e91..9156b76 100644
--- a/Package.swift
+++ b/Package.swift
@@ -39,6 +39,7 @@ let package = Package(
             dependencies: [
                 .target(name: "APNSCore"),
                 .target(name: "APNS"),
+                .target(name: "APNSURLSession"),
                 .target(name: "APNSTestServer"),
                 .product(name: "Crypto", package: "swift-crypto"),
                 .product(name: "NIOPosix", package: "swift-nio"),
diff --git a/Package@swift-5.10.swift b/Package@swift-5.10.swift
index 5d40a0c..3fd4d0d 100644
--- a/Package@swift-5.10.swift
+++ b/Package@swift-5.10.swift
@@ -39,6 +39,7 @@ let package = Package(
             dependencies: [
                 .target(name: "APNSCore"),
                 .target(name: "APNS"),
+                .target(name: "APNSURLSession"),
                 .target(name: "APNSTestServer"),
                 .product(name: "Crypto", package: "swift-crypto"),
                 .product(name: "NIOPosix", package: "swift-nio"),
diff --git a/Sources/APNSURLSession/APNSUrlSessionClient.swift b/Sources/APNSURLSession/APNSUrlSessionClient.swift
index c70c6ed..f5188d2 100644
--- a/Sources/APNSURLSession/APNSUrlSessionClient.swift
+++ b/Sources/APNSURLSession/APNSUrlSessionClient.swift
@@ -37,30 +37,32 @@ public struct APNSURLSessionClient: APNSClientProtocol {
     
         /// Make request
         let (data, response) = try await URLSession.shared.data(for: urlRequest)
-        
+
         /// Unwrap response
-        guard let response = response as? HTTPURLResponse,
-              let apnsIDString = response.allHeaderFields["apns-id"] as? String else {
+        guard let response = response as? HTTPURLResponse else {
             throw APNSUrlSessionClientError.urlResponseNotFound
         }
-        
-        let apnsID = UUID(uuidString: apnsIDString)
-        let apnsUniqueID = (response.allHeaderFields["apns-unique-id"] as? String).flatMap { UUID(uuidString: $0) }
-        
-        /// Detect an error
-        if let errorResponse = try? decoder.decode(APNSErrorResponse.self, from: data) {
-            let error = APNSError(
-                responseStatus: response.statusCode,
-                apnsID: apnsID,
-                apnsUniqueID: apnsUniqueID,
-                apnsResponse: errorResponse,
-                timestamp: errorResponse.timestampInSeconds.flatMap { Date(timeIntervalSince1970: $0) }
-            )
-            throw error
-        } else {
-            /// Return APNSResponse
+
+        /// `value(forHTTPHeaderField:)` performs a case-insensitive lookup, and the
+        /// `apns-id` header may be absent (e.g. on some error responses), so it is optional.
+        let apnsID = response.value(forHTTPHeaderField: "apns-id").flatMap { UUID(uuidString: $0) }
+        let apnsUniqueID = response.value(forHTTPHeaderField: "apns-unique-id").flatMap { UUID(uuidString: $0) }
+
+        /// Success/failure is determined by the HTTP status code, per Apple's APNs spec:
+        /// a `200` is a successful delivery; anything else carries an error reason in the body.
+        if response.statusCode == 200 {
             return APNSResponse(apnsID: apnsID, apnsUniqueID: apnsUniqueID)
         }
+
+        /// Non-200: decode the error body when present, otherwise surface the status code alone.
+        let errorResponse = try? decoder.decode(APNSErrorResponse.self, from: data)
+        throw APNSError(
+            responseStatus: response.statusCode,
+            apnsID: apnsID,
+            apnsUniqueID: apnsUniqueID,
+            apnsResponse: errorResponse,
+            timestamp: errorResponse?.timestampInSeconds.flatMap { Date(timeIntervalSince1970: $0) }
+        )
     }
 
     public func shutdown() async throws {
diff --git a/Tests/APNSTests/APNSURLSessionClientTests.swift b/Tests/APNSTests/APNSURLSessionClientTests.swift
new file mode 100644
index 0000000..c500cbe
--- /dev/null
+++ b/Tests/APNSTests/APNSURLSessionClientTests.swift
@@ -0,0 +1,130 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the APNSwift open source project
+//
+// Copyright (c) 2024 the APNSwift project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of APNSwift project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+#if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
+import APNSCore
+import APNSTestServer
+@testable import APNSURLSession
+import Crypto
+import XCTest
+
+final class APNSURLSessionClientTests: XCTestCase {
+    var server: APNSTestServer!
+    var client: APNSURLSessionClient!
+
+    override func setUp() async throws {
+        try await super.setUp()
+
+        server = APNSTestServer()
+        try await server.start(port: 0)
+
+        client = APNSURLSessionClient(
+            configuration: .init(
+                environment: .custom(url: "http://127.0.0.1", port: server.port),
+                privateKey: try P256.Signing.PrivateKey(pemRepresentation: Self.jwtPrivateKey),
+                keyIdentifier: "MY_KEY_ID",
+                teamIdentifier: "MY_TEAM_ID"
+            )
+        )
+    }
+
+    override func tearDown() async throws {
+        try await server?.shutdown()
+        server = nil
+        client = nil
+        try await super.tearDown()
+    }
+
+    func testSendAlert_success() async throws {
+        let response = try await client.sendAlertNotification(
+            Self.makeAlert(),
+            deviceToken: Self.validDeviceToken
+        )
+
+        // A 200 must be treated as success even though the body is `{}`.
+        XCTAssertNotNil(response.apnsID)
+    }
+
+    func testSendAlert_propagatesHeadersToServer() async throws {
+        _ = try await client.sendAlertNotification(
+            Self.makeAlert(),
+            deviceToken: Self.validDeviceToken
+        )
+
+        let sent = try XCTUnwrap(server.getSentNotifications().first)
+        XCTAssertEqual(sent.deviceToken, Self.validDeviceToken)
+        XCTAssertEqual(sent.pushType, "alert")
+        XCTAssertEqual(sent.topic, "com.example.app")
+    }
+
+    func testSendAlert_badDeviceTokenThrowsTypedError() async throws {
+        do {
+            _ = try await client.sendAlertNotification(
+                Self.makeAlert(),
+                deviceToken: "not-a-valid-token"
+            )
+            XCTFail("Expected an APNSError to be thrown")
+        } catch let error as APNSError {
+            // The status code must drive the failure (previously the code keyed off
+            // whether the body decoded as an error, ignoring the HTTP status).
+            XCTAssertEqual(error.responseStatus, 400)
+            XCTAssertEqual(error.reason, .badDeviceToken)
+        }
+    }
+
+    func testSendAlert_missingTopicThrowsTypedError() async throws {
+        // Build the request with no topic so the `apns-topic` header is omitted entirely.
+        let request = APNSRequest(
+            message: Self.makeAlert(),
+            deviceToken: Self.validDeviceToken,
+            pushType: .alert,
+            expiration: nil,
+            priority: nil,
+            apnsID: nil,
+            topic: nil,
+            collapseID: nil
+        )
+        do {
+            _ = try await client.send(request)
+            XCTFail("Expected an APNSError to be thrown")
+        } catch let error as APNSError {
+            XCTAssertEqual(error.responseStatus, 400)
+            XCTAssertEqual(error.reason, .missingTopic)
+        }
+    }
+
+    // MARK: - Helpers
+
+    private static let validDeviceToken = String(repeating: "a", count: 64)
+
+    private static func makeAlert() -> APNSAlertNotification<EmptyPayload> {
+        APNSAlertNotification(
+            alert: .init(title: .raw("title")),
+            expiration: .immediately,
+            priority: .immediately,
+            topic: "com.example.app",
+            payload: EmptyPayload()
+        )
+    }
+
+    private static let jwtPrivateKey = """
+    -----BEGIN PRIVATE KEY-----
+    MIGTAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBHkwdwIBAQQg2sD+kukkA8GZUpmm
+    jRa4fJ9Xa/JnIG4Hpi7tNO66+OGgCgYIKoZIzj0DAQehRANCAATZp0yt0btpR9kf
+    ntp4oUUzTV0+eTELXxJxFvhnqmgwGAm1iVW132XLrdRG/ntlbQ1yzUuJkHtYBNve
+    y+77Vzsd
+    -----END PRIVATE KEY-----
+    """
+}
+#endif