True open communication is where employees are encouraged to share their thoughts and concerns, both good and bad, without the worry of retaliation from management when the feedback is bad. Many companies claim to have open communication, but very few actually practice it.
The biggest factor to achieving open communication is establishing trust. Employees need to be able to trust their employer will not deny them raises and other compensation for disagreeing with a policy and discussing it with their manager. They also need to feel safe taking their feedback to management. If the wrong people are in the wrong jobs, it hinders the ability to provide an open communication culture.