The Vonage developer portal has added a "Run in Postman" button to its Postman page, making it easier for developers to explore and integrate the company's APIs using the popular tool. This feature allows users to access the Vonage API Calls, organized into a collection, with minimal work involved, and also provides features such as environment variables and a pre-configured Vonage Environment. The developer portal also links to the main Postman network for browsing, and includes a tutorial on using the Postman Collection to explore the Numbers API, which allows developers to manage virtual number inventory programmatically.