1. Replicate the search in the Skype4B client. Does the same issue occur? If yes, this would indicate a Skype4B environment issue. If no, proceed to step 2.
2. Verify the “All Searches Filter” field is empty in Options | Search in Attendant Pro.
3. Verify that search is set to basic in Options | Search in Attendant Pro
4. Test if there are there no search results or only a few results. If there are a few search results returned, check if the contacts are in the user’s personal contacts list, Suggested Contacts, or Skype4B contacts lists in Outlook. If partial or no results are returned, or if contacts only from Outlook are returned, follow the instructions below to check the Skype4B address book.
Ctrl + right click the Skype4B tray icon and select “Configuration information” from the list. In the Skype for Business Configuration information window, find “GAL or Server Based Search” from the list.
If it is set to "Server based search", have your Skype4B admin check if the missing numbers are listed in the Invalid_AD_Phone_Numbers.txt file in your Skype4B address book share. Click HERE for more details. If no, proceed to step 5.
If it is set to “GAL search”, browse to C:\Users\<UserProfile>\AppData\Local\Microsoft\Office\<VersionNumber>\Lync\sip_user@domain\. Do you see a GalContacts.db file in this folder?
If no, Install all updates for the Skype4B client and wait 24 hours. If the file still does not appear, alert your Skype4B admin that your Skype4B environment has a Skype4B address book problem.
If yes, use Notepad to open the GalContacts.db file. In Notepad, select edit > find. Search for the missing user’s SIP address. Is the user listed? Is the user’s DID/Mobile phone numbers listed? If no, this is a Skype4B address book issue. If all the correct contact information is listed, proceed to set 5.
5. Perform a full/online repair install of the Skype4B client/Office.
6. Use Advanced Search.