Switching between the Skype for Business and the Lync 2013 client user interfaces

Edit Registry Binary Value for switching between Skype for Business and the Lync 2013.

Open windows Registry
Start >> Run >> regedit >>
Navigate to Registry key [HKEY_CURRENT_USER\Software\Microsoft\Office\Lync]
The key should look like the following:
"CanSharePptInCollab"=dword:00000001
"CanShareOneNoteInCollab"=dword:00000001
"CanAppShareInCollab"=dword:00000001
"EnableSkypeUI"=hex:00,00,00,00
Double click to open the key and edit last binary digit
The Value name must be EnableSkypeUI   , and the Value data must be set to 00 00 00 00  - For Lync.
The Value name must be EnableSkypeUI   , and the Value data must be set to 00 00 00 01 - For Skype for Business.
If you do not see the EnableSkypeUI key after installing the Skype for Business update you will need to create the Key.

NOTE: Please note that this behavior will be affected by how your Client Access Policy Configuration.
Grant-CsClientPolicy –PolicyName ClientPolicyEnableSkypeUI - The user will continue using the Skype for Business client user interface.
Grant-CsClientPolicy –PolicyName ClientPolicyDisableSkypeUI - The user will be asked to switch to the Skype for Business (Lync) client user interface. They can switch later.

-Thanks
@ Roshan