This is a summary of creating a SwiftUI application that uses the Vonage Client SDK for iOS to make calls to a specified phone number. The application has three parts: the Vonage application, the webhook server, and the iOS application. The Vonage application requires two URLs, an answer_url and an event_url, which are used to handle incoming and outgoing calls. The webhook server exposes two URLs that return a Call Control Object with instructions for Vonage to connect the app to the specified phone number. The iOS application creates a new project in Xcode, installs the Vonage Client SDK as a dependency, and sets up the model class to handle delegate calls from the Client SDK. The model class also handles microphone permissions, logging in as the Alice user with the Client SDK, and implementing required delegate functions for voice client events. Finally, the application creates a SwiftUI view that displays the status of the Client SDK and allows the user to enter a phone number, start a call, or end a call.