diff --git a/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/Microsoft.Communication/AzureCommunicationServices.tsp b/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/Microsoft.Communication/AzureCommunicationServices.tsp
index 6571a63458ba..649205b3410d 100644
--- a/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/Microsoft.Communication/AzureCommunicationServices.tsp
+++ b/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/Microsoft.Communication/AzureCommunicationServices.tsp
@@ -221,6 +221,9 @@ model AcsSmsReceivedEventData extends AcsSmsEventBaseProperties {
   /** The time at which the SMS was received */
   @madeRequired(ServiceApiVersions.v2024_01_01)
   receivedTimestamp: utcDateTime;
+
+  /** Number of segments in the message */
+  segmentCount: int32;
 }
 
 //TODO: This might need some fixing
diff --git a/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2018-01-01/sms_received.json b/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2018-01-01/sms_received.json
index 0c5a91ed9140..de5c1b11ca3d 100644
--- a/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2018-01-01/sms_received.json
+++ b/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2018-01-01/sms_received.json
@@ -9,7 +9,8 @@
     "From": "15555555555",
     "To": "15555555555",
     "Message": "Great to connect with ACS events",
-    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z"
+    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z",
+    "SegmentCount": 1
   },
   "specversion": "1.0",
   "operationId": "SMSReceivedEventName",
diff --git a/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2024-01-01/sms_received.json b/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2024-01-01/sms_received.json
index 0c5a91ed9140..de5c1b11ca3d 100644
--- a/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2024-01-01/sms_received.json
+++ b/specification/eventgrid/Azure.Messaging.EventGrid.SystemEvents/examples/2024-01-01/sms_received.json
@@ -9,7 +9,8 @@
     "From": "15555555555",
     "To": "15555555555",
     "Message": "Great to connect with ACS events",
-    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z"
+    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z",
+    "SegmentCount": 1
   },
   "specversion": "1.0",
   "operationId": "SMSReceivedEventName",
diff --git a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json
index 96a1e7fdcdb1..e4114d3ea68a 100644
--- a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json
+++ b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json
@@ -1357,8 +1357,16 @@
           "description": "The time at which the SMS was received",
           "format": "date-time",
           "type": "string"
+        },
+        "segmentCount": {
+          "description": "Number of segments in the message",
+          "format": "int32",
+          "type": "integer"
         }
-      }
+      },
+      "required": [
+        "segmentCount"
+      ]
     },
     "AcsRecordingFileStatusUpdatedEventData": {
       "description": "Schema of the Data property of an EventGridEvent for a Microsoft.Communication.RecordingFileStatusUpdated event.",
diff --git a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/cloud-events-schema/sms_received.json b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/cloud-events-schema/sms_received.json
index c21b90c2e58b..129f5ddc2f2b 100644
--- a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/cloud-events-schema/sms_received.json
+++ b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/cloud-events-schema/sms_received.json
@@ -9,7 +9,8 @@
     "From": "15555555555",
     "To": "15555555555",
     "Message": "Great to connect with ACS events",
-    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z"
+    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z",
+    "SegmentCount": 1
   },
   "specversion": "1.0"
 }
diff --git a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/event-grid-schema/sms_received.json b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/event-grid-schema/sms_received.json
index cd1924f74fa2..fa0d9b99774b 100644
--- a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/event-grid-schema/sms_received.json
+++ b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/examples/event-grid-schema/sms_received.json
@@ -7,7 +7,8 @@
     "From": "15555555555",
     "To": "15555555555",
     "Message": "Great to connect with ACS events",
-    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z"
+    "ReceivedTimestamp": "2020-09-18T00:27:45.32Z",
+    "SegmentCount": 1
   },
   "eventType": "Microsoft.Communication.SMSReceived",
   "dataVersion": "1.0",
diff --git a/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2018-01-01/GeneratedSystemEvents.json b/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2018-01-01/GeneratedSystemEvents.json
index 60a997e9bee1..52998160d08c 100644
--- a/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2018-01-01/GeneratedSystemEvents.json
+++ b/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2018-01-01/GeneratedSystemEvents.json
@@ -2429,8 +2429,16 @@
           "type": "string",
           "format": "date-time",
           "description": "The time at which the SMS was received"
+        },
+        "segmentCount": {
+          "type": "integer",
+          "format": "int32",
+          "description": "Number of segments in the message"
         }
       },
+      "required": [
+        "segmentCount"
+      ],
       "allOf": [
         {
           "$ref": "#/definitions/AcsSmsEventBaseProperties"
diff --git a/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2024-01-01/GeneratedSystemEvents.json b/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2024-01-01/GeneratedSystemEvents.json
index 7d18fde4a6ea..9b224b2490ff 100644
--- a/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2024-01-01/GeneratedSystemEvents.json
+++ b/specification/eventgrid/data-plane/Microsoft.EventGrid/stable/2024-01-01/GeneratedSystemEvents.json
@@ -2482,10 +2482,16 @@
           "type": "string",
           "format": "date-time",
           "description": "The time at which the SMS was received"
+        },
+        "segmentCount": {
+          "type": "integer",
+          "format": "int32",
+          "description": "Number of segments in the message"
         }
       },
       "required": [
-        "receivedTimestamp"
+        "receivedTimestamp",
+        "segmentCount"
       ],
       "allOf": [
         {