diff --git a/33128/r18/TS33128Payloads.asn b/33128/r18/TS33128Payloads.asn
index aa9398d8e6e389b49722b2783ec97d7052700e82..1e6d4f811aa9c86be991a178cf1cd66e72c4e242 100644
--- a/33128/r18/TS33128Payloads.asn
+++ b/33128/r18/TS33128Payloads.asn
@@ -3762,20 +3762,27 @@ PTCAccessPolicyFailure  ::= ENUMERATED
 -- See clause 7.12.4.2.1 for details of this structure
 IMSMessage ::= SEQUENCE
 {
-    payload               [1] IMSPayload,
-    sessionDirection      [2] SessionDirection,
-    voIPRoamingIndication [3] VoIPRoamingIndication OPTIONAL,
-    location              [6] Location OPTIONAL
+    payload                    [1] IMSPayload,
+    sessionDirection           [2] SessionDirection,
+    voIPRoamingIndication      [3] VoIPRoamingIndication OPTIONAL,
+    -- Tag [4] is not used.
+    -- Tag [5] is not used.
+    location                   [6] Location OPTIONAL,
+    accessNetworkInformation   [4971] SEQUENCE OF SIPAccessNetworkInformation OPTIONAL,
+    cellularNetworkInformation [4972] SEQUENCE OF SIPCellularNetworkInformation OPTIONAL
 }
 -- See clause 7.12.4.2.2 for details of this structure
 StartOfInterceptionForActiveIMSSession ::= SEQUENCE
 {
-    originatingId         [1] SEQUENCE OF IMPU,
-    terminatingId         [2] IMPU,
-    sDPState              [3] SEQUENCE OF OCTET STRING OPTIONAL,
-    diversionIdentity     [4] IMPU OPTIONAL,
-    voIPRoamingIndication [5] VoIPRoamingIndication OPTIONAL,
-    location              [7] Location OPTIONAL
+    originatingId              [1] SEQUENCE OF IMPU,
+    terminatingId              [2] IMPU,
+    sDPState                   [3] SEQUENCE OF OCTET STRING OPTIONAL,
+    diversionIdentity          [4] IMPU OPTIONAL,
+    voIPRoamingIndication      [5] VoIPRoamingIndication OPTIONAL,
+    -- Tag [6] is not used.
+    location                   [7] Location OPTIONAL,
+    accessNetworkInformation   [4971] SEQUENCE OF SIPAccessNetworkInformation OPTIONAL,
+    cellularNetworkInformation [4972] SEQUENCE OF SIPCellularNetworkInformation OPTIONAL
 }
 
 -- See clause 7.12.4.2.3 for the details.
@@ -6330,4 +6337,16 @@ OGCURN ::= UTF8String
 -- TS 29.572 [24], clause 6.1.6.2.15
 MethodCode ::= INTEGER (16..31)
 
+SIPAccessNetworkInformation ::= SEQUENCE
+{
+    accessNetworkInfo [1] UTF8String,
+    servingPLMN       [2] PLMNID OPTIONAL
+}
+
+SIPCellularNetworkInformation ::= SEQUENCE
+{
+    cellularNetworkInfo  [1] UTF8String,
+    servingPLMN          [2] PLMNID OPTIONAL
+}
+
 END