In Skype for business you can store all your contacts in the way best suited for you, from automatically being connected to everyone on the same Office 365 tenant as yourself, to being able to add external skype users.
Manage your contacts in four separate default categories: (explaining what each group does)
Groups allows you to manage your contacts how you want, customize with more groups and add and remove users as you decide
Status will show you all your contacts and what there current contact status is this will normally be between "Online, Busy, Away and Offline"
Relationships will lay out your contacts with how you know people in your contacts, these catagories can be altered by right clicking the person you wish to move, and selecting " Change Privacy Relationship" and by selecting the correct field as seen below:
New will show you the newest additions to your Skype for business
This tab will allow you to go through your old conversation through Skype for Business
You can choose to filter your views between All, Missed and Calls to have easier views
The phone function in Skype for Business work exactly as you would a regular Hard Phone.
Your number for external contacts to use is made readily available to you under the dial pad highlighted in the yellow box below and any voice mails are made ready for you to playback
Split Voicemail section:
You can change your voicemail settings via the red circled option below:
At the bottom of this tab you are able to manage your phone and change where it rings, this will allow you turn off Call Forwarding, Set a new Call forward and allow you to set it so that multiple phones can ring at once.
Your Meetings Tab will show every Skype meeting you have planned for the near future. (add a meeting, and how it connects to Outlook, show how to add a meeting and to join a meeting)
From here you can create new meetings, invite contacts, and manage your meetings for the day