Making phone calls directly from HubSpot (Phone calls can only be made for individuals with paid seats)
In the upper left corner select Contacts -> Contacts or Companies
In selecting a known contact or company, Calls will appear in the middle section to begin making calls
Select Make a phone call (Phone calls can only be made for individuals with paid seats)
With the phone number attached to the call to be made, select either call from the phone number that was added to your profile or from the browser