Nar Shadda is bugged and many people can't get a call from Visquis even after completing all quests on the planet. I had that problem too, but I found a way to solve this. It includes save game editing, and you may call it cheating, but since it's the only way to advance...
-Download The Sith Lords Savegame Editor (KSE) v3.3.2 from
http://www.starwarsknights.com/tools.php
-Backup your savegames
-Start the editor. It should display list of savegames. Select one
-Open "Globals", then "Booleans"
-Select "300NAR_Visquis_call"
-If "yes" is marked, then you have already received the call, but game skipped it. It happens
-Switch to "no" and "commit changes". Editor will save changes to your save file
And that should do it. Walk around Nar Shadda to trigger the call. I received it immediately after going from one area to another.