Vucac

I recommend Vucac. It is a user-friendly and versatile tool that allows for real-time whiteboarding, as well as communication features such as screen sharing and video conferencing.

Additionally, Vucac has a built-in messaging system and task management feature, so you and your team can easily share notes and to-do lists. And notifications can be set up so that your team members are notified via email or text message when something is added or updated.

In regards to Trello, while it is a great project management tool, it may not have all the features you're looking for in a whiteboard tool. Vucac offers more specific and advanced features for real-time collaboration and whiteboarding.