diff --git a/src/blackmisc/aviation/callsignobjectlist.cpp b/src/blackmisc/aviation/callsignobjectlist.cpp
index b965017cc..348190e32 100644
--- a/src/blackmisc/aviation/callsignobjectlist.cpp
+++ b/src/blackmisc/aviation/callsignobjectlist.cpp
@@ -14,6 +14,7 @@
 #include "blackmisc/aviation/aircraftsituationlist.h"
 #include "blackmisc/aviation/flightplanlist.h"
 #include "blackmisc/network/clientlist.h"
+#include "blackmisc/network/userlist.h"
 #include "blackmisc/predicates.h"
 
 #include <QtGlobal>
@@ -303,6 +304,7 @@ namespace BlackMisc
         template class BLACKMISC_EXPORT_DEFINE_TEMPLATE ICallsignObjectList<BlackMisc::Simulation::CSimulatedAircraft, BlackMisc::Simulation::CSimulatedAircraftList>;
         template class BLACKMISC_EXPORT_DEFINE_TEMPLATE ICallsignObjectList<BlackMisc::Simulation::CInterpolationAndRenderingSetupPerCallsign, BlackMisc::Simulation::CInterpolationSetupList>;
         template class BLACKMISC_EXPORT_DEFINE_TEMPLATE ICallsignObjectList<BlackMisc::Network::CClient, BlackMisc::Network::CClientList>;
+        template class BLACKMISC_EXPORT_DEFINE_TEMPLATE ICallsignObjectList<BlackMisc::Network::CUser, BlackMisc::Network::CUserList>;
         //! \endcond
 
     } // namespace
diff --git a/src/blackmisc/aviation/callsignobjectlist.h b/src/blackmisc/aviation/callsignobjectlist.h
index f0d69a875..276178911 100644
--- a/src/blackmisc/aviation/callsignobjectlist.h
+++ b/src/blackmisc/aviation/callsignobjectlist.h
@@ -43,6 +43,8 @@ namespace BlackMisc
     {
         class CClient;
         class CClientList;
+        class CUser;
+        class CUserList;
     }
 
     namespace Aviation
@@ -142,6 +144,7 @@ namespace BlackMisc
         extern template class BLACKMISC_EXPORT_DECLARE_TEMPLATE ICallsignObjectList<BlackMisc::Simulation::CSimulatedAircraft, BlackMisc::Simulation::CSimulatedAircraftList>;
         extern template class BLACKMISC_EXPORT_DECLARE_TEMPLATE ICallsignObjectList<BlackMisc::Simulation::CInterpolationAndRenderingSetupPerCallsign, BlackMisc::Simulation::CInterpolationSetupList>;
         extern template class BLACKMISC_EXPORT_DECLARE_TEMPLATE ICallsignObjectList<BlackMisc::Network::CClient, BlackMisc::Network::CClientList>;
+        extern template class BLACKMISC_EXPORT_DECLARE_TEMPLATE ICallsignObjectList<BlackMisc::Network::CUser, BlackMisc::Network::CUserList>;
         //! \endcond
 
     } //namespace
diff --git a/src/blackmisc/network/user.cpp b/src/blackmisc/network/user.cpp
index aa38bf132..e0a1a5610 100644
--- a/src/blackmisc/network/user.cpp
+++ b/src/blackmisc/network/user.cpp
@@ -63,10 +63,12 @@ namespace BlackMisc
             return this->getId();
         }
 
-        void CUser::setCallsign(const CCallsign &callsign)
+        bool CUser::setCallsign(const CCallsign &callsign)
         {
+            if (m_callsign == callsign) { return false; }
             m_callsign = callsign;
             this->deriveHomeBaseFromCallsign();
+            return true;
         }
 
         QString CUser::convertToQString(bool i18n) const
diff --git a/src/blackmisc/network/user.h b/src/blackmisc/network/user.h
index 6298036ad..46bbf7423 100644
--- a/src/blackmisc/network/user.h
+++ b/src/blackmisc/network/user.h
@@ -146,7 +146,7 @@ namespace BlackMisc
             const Aviation::CCallsign &getCallsign() const { return m_callsign; }
 
             //! Set associated callsign
-            void setCallsign(const Aviation::CCallsign &callsign);
+            bool setCallsign(const Aviation::CCallsign &callsign);
 
             //! \copydoc BlackMisc::Mixin::Icon::toIcon()
             CIcon toIcon() const { return this->getCallsign().toIcon(); }
diff --git a/src/blackmisc/network/userlist.h b/src/blackmisc/network/userlist.h
index a5fef9c57..2267b3d57 100644
--- a/src/blackmisc/network/userlist.h
+++ b/src/blackmisc/network/userlist.h
@@ -11,11 +11,13 @@
 #ifndef BLACKMISC_NETWORK_USERLIST_H
 #define BLACKMISC_NETWORK_USERLIST_H
 
-#include "blackmisc/blackmiscexport.h"
-#include "blackmisc/collection.h"
+#include "blackmisc/aviation/callsignobjectlist.h"
 #include "blackmisc/network/user.h"
+#include "blackmisc/collection.h"
 #include "blackmisc/sequence.h"
 #include "blackmisc/variant.h"
+#include "blackmisc/blackmiscexport.h"
+
 #include <QMetaType>
 
 namespace BlackMisc
@@ -25,7 +27,8 @@ namespace BlackMisc
         //! Value object encapsulating a list of voice rooms.
         class BLACKMISC_EXPORT CUserList :
             public CSequence<CUser>,
-            public BlackMisc::Mixin::MetaType<CUserList>
+            public Aviation::ICallsignObjectList<CUser, CUserList>,
+            public Mixin::MetaType<CUserList>
         {
         public:
             BLACKMISC_DECLARE_USING_MIXIN_METATYPE(CUserList)