Accept any of the invite notifications

`Alt` + `C`

All hotkeys for Skype for Business (Lync) 2016 (Windows)

General Usually gets to start Skype	`win` , then type 'skype'
General Accept an incoming invite notification	`Win` + `Shift` + `O`
General Decline an invite notification	`Win` + `Esc`
General Mute/unmute audio	`Win` + `F4`
General Turn camera on/off	`Win` + `F5`
General Put focus on the application sharing toolbar	`Ctrl` + `Shift` + `Space`
General Open the main window and put focus in the search box.	`Ctrl` + `Alt` + `Shift` + `3`
General Take back control when sharing your screen	`Ctrl` + `Alt` + `Space`
General Stop sharing your screen.	`Ctrl` + `Shift` + `S`
Main Window Move to the Contacts list tab	`Ctrl` + `1`
Main Window Move to the persistent chat tab	`Ctrl` + `2`
Main Window Move to the Conversation list tab	`Ctrl` + `3`
Main Window Move to the Phone tab	`Ctrl` + `4`
Main Window Open the System menu. Alt opens the menu bar	`Alt` + `Space`
Main Window Open the File menu	`Alt` + `F`
Main Window Start Meet Now	`Alt` + `M`
Main Window Open the Tools menu	`Alt` + `T`
Main Window Open the Help menu	`Alt` + `H`
Contacts list Delete the selected custom group or contact.	`Delete`
Contacts list Move the selected group up/down	`Alt` + `Arrow Up` / `Alt` + `Arrow Down`
Contacts list On the shortcuts menu - open the selected contact or group contacts card	`Alt` + `Enter`
Contacts list Collapse or expand the selected group	`Space`
Contacts list Remove the selected contact from the Contacts list	`Shift` + `Delete`
Conversation window Accept any of the invite notifications	`Alt` + `C`
Conversation window Ignore any of the invite notifications	`Alt` + `L`
Conversation window Save as for files sent in Conversation Window	`Alt` + `S`
Conversation window Invite a contact to an existing conversation.	`Alt` + `V`
Conversation window Rejoin audio in a meeting.	`Alt` + `R`
Conversation window Close the Conversation window	`Alt` + `F4`
Conversation window Save the contents of IM history	`Ctrl` + `S`
Conversation window Show/ hide instant message area	`Ctrl` + `W`
Conversation window Send File	`Ctrl` + `F`
Conversation window Take Notes with OneNote	`Ctrl` + `N`
Conversation window Show/ hide the participant list.	`Ctrl` + `R`
Conversation window Navigate right /left to the next element in the Conversation window	`Ctrl` + `Shift` + `Alt` + `Arrow Right` / `Arrow Left`
Conversation window Add video/end video.	`Ctrl` + `Shift` + `Enter`
Conversation window Hold or resume an ongoing audio conversation.	`Ctrl` + `Shift` + `H`
Conversation window Mark conversation Important	`Ctrl` + `Shift` + `I`
Conversation window Show or hide the sharing stage	`Ctrl` + `Shift` + `Y`
Conversation window Switch to compact view	`Ctrl` + `Shift` + `P`
Conversation window Switch to content-only view	`Ctrl` + `Shift` + `K`
Conversation window Add audio/end audio	`Ctrl` + `Enter`
Instant Messaging Focus to your IM input area.	`Ctrl` + `Shift` + `M`
Instant Messaging Add line break	`Shift` + `Enter`
Instant Messaging Select all content	`Ctrl` + `A`
Instant Messaging Format bold	`Ctrl` + `B`
Instant Messaging Format italic	`Ctrl` + `L`
Instant Messaging Format underline	`Ctrl` + `U`
Instant Messaging Change Font Color	`Ctrl` + `Shift` + `F`
Instant Messaging Open a file that’s been received.	`Alt` + `P`
Instant Messaging Decline a file that’s been sent.	`Alt` + `D`
Instant Messaging Undo / Redo	`Ctrl` + `Z` / `Ctrl` + `Y`
Instant Messaging Cut/ Copy/ Paste	`Ctrl` + `X` / `Ctrl` + `C` / `Ctrl` + `V`
Instant Messaging Save the IM conversation.	`F12`
Instant Messaging For Video - Switch to Full Screen	`F5`
Instant Messaging For Video - Exit full-screen video.	`Esc`
Instant Messaging For Video - Toggle Pop-Out Gallery	`Ctrl` + `Shift` + `O`
Instant Messaging For Video - Lock video for everyone in the meeting	`Ctrl` + `Shift` + `L`
Call Control Display the Dial pad	`Ctrl` + `Shift` + `D`
Call Control End a call	`Alt` + `Q`
Call Control Put a call on hold	`Ctrl` + `Shift` + `H`
Conversation or Meeting Stage Stop sharing.	`Alt` + `T`
Conversation or Meeting Stage Manage presentable content.	`Ctrl` + `Shift` + `E`
Conversation or Meeting Stage Show or hide the sharing stage.	`Ctrl` + `Shift` + `Y`
Conversation or Meeting Stage Force pending L1 alert into view in full screen.	`Ctrl` + `Shift` + `A`
Conversation or Meeting Stage Switch to speaker view.	`Ctrl` + `Shift` + `J`
Conversation or Meeting Stage Switch to gallery view.	`Ctrl` + `Shift` + `L`
Conversation or Meeting Stage Tab out of the sharing region in a forward direction, and/or tab out of the sharing region in a backward direction.	`Ctrl` + `Alt` + `Arrow Right` / `Ctrl` + `Alt` + `Arrow Left`
Conversation or Meeting Stage Switch to Full Screen	`F5`
Conversation or Meeting Stage Exit full-screen video.	`Esc`
Conversation Environment Delete selected items	`Delete`
Conversation Environment Move top / move to bottom of list	`Home` / `End`
Conversation Environment Move one page up / move one page down	`Page Up` / `Page Down`
Conversation Environment Move up / move down in conversation.	`Arrow Up`
PowerPoint Sharing With slide in focus - Access controls (Prev arrow, Next arrow, Thumbnails, and Notes)	`Tab`
PowerPoint Sharing With slide in focus - Move to previous slide / next slide (or next click)	`Arrow Right` / `Arrow Left`
PowerPoint Sharing With thumbnails in focus - Move to next/ move to previous thumbnail	Left / `Arrow Right`
PowerPoint Sharing With thumbnails in focus - Move to first / move to last slide thumbnail	`Home` / `End`
Tabbed conversations Set focus on tab item in tabbed conversation view	`Ctrl` + `Shift` + `T`
Tabbed conversations Switch to the next tab / switch to previous tab	`Ctrl` + `Tab` / `Ctrl` + `Shift` + `Tab`
Tabbed conversations Switch to a specific tab number and put keyboard focus in that conversation. Ctrl+1.	`Ctrl` + `1` … `9`
Tabbed conversations Undock/dock conversation from/to the tab window	`Ctrl` + `O`
Tabbed conversations Close a tab.	`Esc`
Tabbed conversations Open tab window’s system menu	`Alt` + `Space`
The Rest In Main Window - As a delegate, transfer a call to someone else’s work number	`Ctrl` + `1` / `Ctrl` + `Shift` + `1`
The Rest in Calls - Transfer: Open the contact picker during a peer-to-peer call. (Not available in Lync Basic or with all Office 365 subscriptions.)	`Ctrl` + `Shift` + `T`