diff --git a/src/chat/chat-room/server-group-chat-room-stub.cpp b/src/chat/chat-room/server-group-chat-room-stub.cpp
index 90950be2f..03d88eea3 100644
--- a/src/chat/chat-room/server-group-chat-room-stub.cpp
+++ b/src/chat/chat-room/server-group-chat-room-stub.cpp
@@ -215,4 +215,10 @@ void ServerGroupChatRoom::leave () {}
 
 void ServerGroupChatRoom::onFirstNotifyReceived (const IdentityAddress &addr) {}
 
+// -----------------------------------------------------------------------------
+
+ostream &operator<< (ostream &stream, const ServerGroupChatRoom *chatRoom) {
+	return stream << "ServerGroupChatRoom [" << chatRoom << "]";
+}
+
 LINPHONE_END_NAMESPACE
diff --git a/src/chat/chat-room/server-group-chat-room.h b/src/chat/chat-room/server-group-chat-room.h
index fa4fd0ab4..57d49dcfc 100644
--- a/src/chat/chat-room/server-group-chat-room.h
+++ b/src/chat/chat-room/server-group-chat-room.h
@@ -93,6 +93,8 @@ private:
 	L_DISABLE_COPY(ServerGroupChatRoom);
 };
 
+std::ostream &operator<< (std::ostream &stream, const ServerGroupChatRoom *chatRoom);
+
 LINPHONE_END_NAMESPACE
 
 #endif // ifndef _L_SERVER_GROUP_CHAT_ROOM_H_
diff --git a/src/conference/participant-device.cpp b/src/conference/participant-device.cpp
index e04ecef3f..4c147a38d 100644
--- a/src/conference/participant-device.cpp
+++ b/src/conference/participant-device.cpp
@@ -47,4 +47,18 @@ void ParticipantDevice::setConferenceSubscribeEvent (LinphoneEvent *ev) {
 	mConferenceSubscribeEvent = linphone_event_ref(ev);
 }
 
+ostream &operator<< (ostream &stream, ParticipantDevice::State state) {
+	switch (state) {
+		case ParticipantDevice::State::Joining:
+			return stream << "Joining";
+		case ParticipantDevice::State::Present:
+			return stream << "Present";
+		case ParticipantDevice::State::Leaving:
+			return stream << "Leaving";
+		case ParticipantDevice::State::Left:
+			return stream << "Left";
+	}
+	return stream;
+}
+
 LINPHONE_END_NAMESPACE
diff --git a/src/conference/participant-device.h b/src/conference/participant-device.h
index f1abe8e1e..e10da6394 100644
--- a/src/conference/participant-device.h
+++ b/src/conference/participant-device.h
@@ -72,6 +72,8 @@ private:
 	L_DISABLE_COPY(ParticipantDevice);
 };
 
+std::ostream &operator<< (std::ostream &stream, ParticipantDevice::State state);
+
 LINPHONE_END_NAMESPACE
 
 #endif // ifndef _L_PARTICIPANT_DEVICE_H_