another note for today about Dynamics CRM licensing elements.
So, let's get started.
External and Internal users for humans and computers
First of all it's worth of mentioning, that Dynamisc CRM can be divided in two main groups: external and internal users. External license is applicable to your customers, to which you would like to give permission to communicate with your CRM instance which aren't your employees. Internal license has two divisions as well. Device lincense or person license. Names are self explanatory, but if to summarize, person lincense or personal CAL is applicable to your employer which has plenty of devices and from each of devices he provides valuable input to your organization. Another situation can appear in your organization, if many users via the same device use your instance of Dynamics CRM. For that cases you can make license for device.
Following picture presents all what I've written visually:
You can have license either for device or for employee.
And for external customers which are your customers and suppliers CAL is not required.
CAL Access modes
That's not all which is related to licensing. You can have three groups of users: Read-Write, Administrative, Non-Interactive users. If first two is in no way puzzle for you, then you can think, why I need Non-Interactive users? Well, that is special license which allow you to use API for any purposes. CRM Online is provided by five non-interactive users, that can be set up for connecting to portals or integrating with CRM.
ESS and ECS licenses
ECS stands for external connector license. That type of license is needed for external customers of your company. For them you use ECS license. ESS stands for employee self service. Imagine that you need to provide to some personell in your company only small bit of permissions and portal. For such an employee you can use ESS license.