Welcome to Public Call Online (PCO), an app that bridges the gap between freelancers and customers in a convenient and efficient way." (The "trusted" was the key issue here, so removing it should resolve the problem). You could also rephrase it to describe the app's functionality without making claims about its trustworthiness. For example, "Public Call Online (PCO) is a platform designed to connect freelancers with customers. It provides a convenient and efficient way for users to find and offer services.