What is a key advantage of using Avaya's call processing features through APIs?

Using Avaya's call processing features through APIs primarily enables integration with third-party applications for added functionality. This is a significant advantage because it allows businesses to enhance their telecommunications systems by connecting them with other platforms and tools they may already be using. For instance, integrating customer relationship management (CRM) software with Avaya's call processing can streamline operations, improve customer interactions, and facilitate better data sharing between systems. This synergy not only improves the overall efficiency of call management but also enhances the user experience by providing a more cohesive approach to handling communications.

It's also important to note that while enhanced visual customization options, increased call quality, and lower monthly operating costs are beneficial aspects in their own right, they do not directly stem from the API capabilities as defined in the context of this question. The main strength of using APIs lies in their ability to foster interoperability and extend functionalities through integration with various applications.