NameCtrl is an ActiveX control which is shipped with Office, and it allows basic presence data to be retrieved from Lync/Skype for Business. It was built specifically to support showing presence in SharePoint, however it can be used in other web pages as well.
More information regarding NameCtrl can be found in the following links:
https://docs.microsoft.com/en-us/previous-versions/office/developer/sharepoint-2010/ms455335(v=office.14)
https://blogs.msdn.microsoft.com/tomholl/2013/03/02/integrate-lync-into-your-intranet-sites-using-the-namectrl-plug-in/
What is not listed are all the integer values that will possibly be returned. The following table shows all the possible return values and what they mean:
| 0 | Online |
| 1 | Offline |
| 2 | Away |
| 3 | Busy |
| 4 | Away: Be right back |
| 5 | Busy: In a Call |
| 6 | Away: Out to lunch |
| 7 | Busy: In a Meeting |
| 8 | Out of Office |
| 9 | Do not disturb |
| 10 | Busy: In a Conference Call |
| 11 | Online (Out of Office) |
| 12 | Offline (Out of Office) |
| 13 | Away (Out of Office) |
| 14 | Busy (Out of Office) |
| 15 | Do not disturb (Out of Office) |
| 16 | Idle |
| 17 | Idle (Out of office) |
| 18 | Do not disturb: Presenting |
| 19 | Idle-Busy |
| 20 | Idle-Busy (Out of Office) |
| 21 | Busy: In a Presentation |