Once a week we have a half hour session where we talk about a few features in our application or explain a customer question to our employees(sales, support, technical services, and development). This session is to teach our employees the application we sell and to help them improve the service to our customers. Once every two weeks, this session is mandatory. Unfortunately, some of our employees do not take this too seriously.
How can we, as developers, gain more involvement from the rest of the company? And make them understand the application we're building, selling and supporting more?
Ask them to present the topic in front of you after some days from the session day.
Another good way is to make them suggest new features and modifications in the project.