One method to get your teams to come together is to create a service level agreement (SLA). Other methods, like committing to regular meetings, can be used
There are several ways departments can effectively communicate clear commitments to each other.
One popular method is to draw up a service level agreement, a document that specifies measurable goals and deliverables that departments are committing to providing one another. Essentially, it clarifies duties, distributes responsibility, and creates a foundation for accountability.
Whether or not you use an SLA, your teams must come together to understand their different roles in accomplishing the goal. It may mean committing to consistent meetings, quarterly reviews, or creating an internal process document.
Whatever commitment method you decide on must result in a real commitment.