You can build custom apps that interact with your business applications to improve customer service and productivity.
Your custom phone app can communicate with other web services available on the network. That could mean your tools for customer relationship management, billing, scheduling, etc., or even a public web service you use to gather information.
Also, you can integrate activity on the phone with your business applications. For example, you could open your app when there's an incoming call and reach out to your CRM tool. You could make note of the call and retrieve information about the caller to display on the phone.
These kind of custom phone apps will let you build a whole new level of communication services for your organization.