Hi Cindy,
You can definitely incorporate actions that happen in your CRM environment into your Marketo lead scoring model. I would highly recommend that you keep your scoring model in Marketo, so that you have one version of the truth and can manage it all centrally.
Typically, for something like 'placed phone call', a Sales person would log an activity. As long as there is something consistent in the subject of the activity they are logging, you can use the 'Activity Was Logged' trigger and use the subject line 'Contains' Phone Call.
Hope that helps!