User visibility - seeing when someone else is working on a project you're working on

We work with a sales and a project management team, and sometimes both of them are editing a project at the same time - perhaps adding additional information in the notes or assigning providers, etc.

Currently this means that someone's work won't be saved due to the system not being able to handle two lots of editing at the same time, and it's impossible to know when this will be the case as the system doesn't warn us until we try and save the work.

We'd like to suggest having some visibility of who is working on that particular project at the moment, like when you log in to a sharepoint file and you can see in the top of the page the person working on the project. Then we know not to try and edit it or can at least talk to the person to see how long they'll be working in there.