List of all Phone Calls with Account Number

I am pulling a list of all phone calls completed today.  My reps call from calls that are Regarding Accounts, Leads, and Opportunities.  The issue is that I am having trouble pulling a list of all of the Account Numbers for the calls that are Regarding Opportunities.  My Opportunities all come from Accounts, that have Account Numbers on them, but I can't get the Account Number to be a column.  I can get the Potential Customer (Regarding) name, but not number/ID.

Thanks for the help.