Index: binaries/data/config/default.cfg
===================================================================
--- binaries/data/config/default.cfg
+++ binaries/data/config/default.cfg
@@ -345,6 +345,7 @@
 attack = true                     ; Show a chat notification if you are attacked by another player
 tribute = true                    ; Show a chat notification if an ally tributes resources to another team member if teams are locked, and all tributes in observer mode
 barter = true                     ; Show a chat notification to observers when a player bartered resources
+phase = true                      ; Show a chat notification when an ally is advancing or has reached a new phase, and all phases in observer mode
 
 [gui.splashscreen]
 enable = true                     ; Enable/disable the splashscreen
Index: binaries/data/mods/public/gui/options/options.json
===================================================================
--- binaries/data/mods/public/gui/options/options.json
+++ binaries/data/mods/public/gui/options/options.json
@@ -278,6 +278,12 @@
 			"label": "Barter",
 			"tooltip": "Show a chat notification to observers when a player bartered resources",
 			"parameters": { "config": "gui.session.notifications.barter" }
+		},
+		{
+			"type": "boolean",
+			"label": "New phase",
+			"tooltip": "Show a chat notification when an ally is advancing or has reached a new phase, and all phases in observer mode",
+			"parameters": { "config": "gui.session.notifications.phase" }
 		}
 	]
 }
Index: binaries/data/mods/public/gui/session/messages.js
===================================================================
--- binaries/data/mods/public/gui/session/messages.js
+++ binaries/data/mods/public/gui/session/messages.js
@@ -128,7 +128,8 @@
 	"diplomacy": msg => formatDiplomacyMessage(msg),
 	"tribute": msg => formatTributeMessage(msg),
 	"barter": msg => formatBarterMessage(msg),
-	"attack": msg => formatAttackMessage(msg)
+	"attack": msg => formatAttackMessage(msg),
+	"phase": msg => formatPhaseMessage(msg)
 };
 
 /**
@@ -394,6 +395,15 @@
 			"targetIsDomesticAnimal": notification.targetIsDomesticAnimal
 		});
 	},
+	"phase": function(notification, player)
+	{
+		addChatMessage({
+			"type": "phase",
+			"player": player,
+			"phaseName": notification.phaseName,
+			"phaseState": notification.phaseState
+		});
+	},
 	"dialog": function(notification, player)
 	{
 		if (player == Engine.GetPlayerID())
@@ -950,6 +960,24 @@
 	});
 }
 
+function formatPhaseMessage(msg)
+{
+	if (Engine.ConfigDB_GetValue("user", "gui.session.notifications.phase") != "true" ||
+	   (msg.player != g_ViewedPlayer && !g_IsObserver && !g_Players[msg.player].isMutualAlly[g_ViewedPlayer]))
+		return "";
+
+	let message = "";
+	if (msg.phaseState == "started")
+		message = translate("%(player)s is advancing to the %(phaseName)s.");
+	else if (msg.phaseState == "completed")
+		message = translate("%(player)s has reached the %(phaseName)s.");
+
+	return sprintf(message, {
+		"player": colorizePlayernameByID(msg.player),
+		"phaseName": getEntityNames(GetTechnologyData(msg.phaseName, g_Players[msg.player].civ))
+	});
+}
+
 function formatChatCommand(msg)
 {
 	if (!msg.text)
Index: binaries/data/mods/public/simulation/ai/petra/chatHelper.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/chatHelper.js
+++ binaries/data/mods/public/simulation/ai/petra/chatHelper.js
@@ -43,15 +43,6 @@
 	markForTranslation("A new trade route is set up with %(_player_)s. Take your share of the profits.")
 ];
 
-m.newPhaseMessages = {
-	"started": [
-		markForTranslation("I am advancing to the %(phase)s.")
-	],
-	"completed": [
-		markForTranslation("I have reached the %(phase)s.")
-	]
-};
-
 m.newDiplomacyMessages = {
 	"ally": [
 		markForTranslation("%(_player_)s and I are now allies.")
Index: binaries/data/mods/public/simulation/ai/petra/headquarters.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/headquarters.js
+++ binaries/data/mods/public/simulation/ai/petra/headquarters.js
@@ -411,20 +411,6 @@
 	}
 };
 
-/** Called by the "town phase" research plan once it's started */
-m.HQ.prototype.OnTownPhase = function(gameState)
-{
-	let phaseName = gameState.getTemplate(gameState.townPhase()).name();
-	m.chatNewPhase(gameState, phaseName, "started");
-};
-
-/** Called by the "city phase" research plan once it's started */
-m.HQ.prototype.OnCityPhase = function(gameState)
-{
-	let phaseName = gameState.getTemplate(gameState.cityPhase()).name();
-	m.chatNewPhase(gameState, phaseName, "started");
-};
-
 /** This code trains citizen workers, trying to keep close to a ratio of worker/soldiers */
 m.HQ.prototype.trainMoreWorkers = function(gameState, queues)
 {
@@ -2213,18 +2199,6 @@
 	this.researchManager.checkPhase(gameState, queues);
 
 	// TODO find a better way to update
-	if (this.currentPhase != gameState.currentPhase())
-	{
-		this.currentPhase = gameState.currentPhase();
-		let phaseName = "Unknown Phase";
-		if (this.currentPhase == 2)
-			phaseName = gameState.getTemplate(gameState.townPhase()).name();
-		else if (this.currentPhase == 3)
-			phaseName = gameState.getTemplate(gameState.cityPhase()).name();
-
-		m.chatNewPhase(gameState, phaseName, "completed");
-	}
-
 	if (this.numActiveBase() > 0)
 	{
 		this.trainMoreWorkers(gameState, queues);
Index: binaries/data/mods/public/simulation/components/Player.js
===================================================================
--- binaries/data/mods/public/simulation/components/Player.js
+++ binaries/data/mods/public/simulation/components/Player.js
@@ -731,6 +731,20 @@
 		this.UpdateSharedLos();
 	else if (msg.tech == this.template.SharedDropsitesTech)
 		this.sharedDropsites = true;
+
+	let cmpDataTemplateManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_DataTemplateManager);
+	let template = cmpDataTemplateManager.GetTechnologyTemplate(msg.tech);
+	// Send a notification for new phase
+	if (msg.tech.startsWith("phase_") && !template.autoResearch)
+	{
+		var cmpGUIInterface = Engine.QueryInterface(SYSTEM_ENTITY, IID_GuiInterface);
+			cmpGUIInterface.PushNotification({
+				"type": "phase",
+				"players": [this.playerID],
+				"phaseName": msg.tech,
+				"phaseState": "completed"
+		});
+	}
 };
 
 Player.prototype.OnDiplomacyChanged = function()
Index: binaries/data/mods/public/simulation/helpers/Commands.js
===================================================================
--- binaries/data/mods/public/simulation/helpers/Commands.js
+++ binaries/data/mods/public/simulation/helpers/Commands.js
@@ -334,6 +334,18 @@
 		var queue = Engine.QueryInterface(cmd.entity, IID_ProductionQueue);
 		if (queue)
 			queue.AddBatch(cmd.template, "technology");
+
+		// if the researched technology is phasing, send a notification to GUI
+		if (cmd.template.startsWith("phase_") && !cmd.template.autoResearch)
+		{
+			var cmpGuiInterface = Engine.QueryInterface(SYSTEM_ENTITY, IID_GuiInterface);
+			cmpGuiInterface.PushNotification({
+				"type": "phase",
+				"players": [player],
+				"phaseName": cmd.template,
+				"phaseState": "started"
+			});
+		}
 	},
 
 	"stop-production": function(player, cmd, data)