diff --git a/specification/communication/data-plane/SipRouting/preview/2021-05-01-preview/communicationservicessiprouting.json b/specification/communication/data-plane/SipRouting/preview/2021-05-01-preview/communicationservicessiprouting.json
index 4af75857762c..54d4052c8241 100644
--- a/specification/communication/data-plane/SipRouting/preview/2021-05-01-preview/communicationservicessiprouting.json
+++ b/specification/communication/data-plane/SipRouting/preview/2021-05-01-preview/communicationservicessiprouting.json
@@ -65,7 +65,7 @@
             "name": "body",
             "description": "Configuration patch.",
             "schema": {
-              "$ref": "#/definitions/SipConfiguration"
+              "$ref": "#/definitions/SipConfigurationPatch"
             }
           }
         ],
@@ -115,6 +115,17 @@
         }
       }
     },
+    "TrunkPatch": {
+      "description": "Represents a SIP trunk patch.",
+      "type": "object",
+      "properties": {
+        "sipSignalingPort": {
+          "format": "int32",
+          "description": "Gets or sets SIP signaling port of the trunk.",
+          "type": "integer"
+        }
+      }
+    },
     "TrunkRoute": {
       "description": "Represents a trunk route for routing calls.",
       "required": [
@@ -169,6 +180,28 @@
           }
         }
       }
+    },
+    "SipConfigurationPatch": {
+      "description": "Represents a SIP configuration patch.",
+      "type": "object",
+      "properties": {
+        "trunks": {
+          "description": "SIP trunks for routing calls.\r\nMap key is trunk's FQDN (1-249 characters).",
+          "maxLength": 250,
+          "type": "object",
+          "additionalProperties": {
+            "$ref": "#/definitions/TrunkPatch"
+          }
+        },
+        "routes": {
+          "description": "Trunk routes for routing calls.",
+          "maxLength": 250,
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/TrunkRoute"
+          }
+        }
+      }
     }
   },
   "parameters": {