diff --git a/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/EpsFallbackReason.aidl b/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/EpsFallbackReason.aidl
new file mode 100644
index 0000000..ebea903
--- /dev/null
+++ b/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/EpsFallbackReason.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"),
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.radio.ims;
+@Backing(type="int") @JavaDerive(toString=true) @VintfStability
+enum EpsFallbackReason {
+  NO_NETWORK_TRIGGER = 1,
+  NO_NETWORK_RESPONSE = 2,
+}
diff --git a/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioIms.aidl b/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioIms.aidl
index f774555..ee5c572 100644
--- a/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioIms.aidl
+++ b/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioIms.aidl
@@ -38,6 +38,7 @@
   oneway void updateImsRegistrationInfo(int serial, in android.hardware.radio.ims.ImsRegistration imsRegistration);
   oneway void startImsTraffic(int serial, in String token, android.hardware.radio.ims.ImsTrafficType imsTrafficType, android.hardware.radio.AccessNetwork accessNetworkType);
   oneway void stopImsTraffic(int serial, in String token);
+  oneway void triggerEpsFallback(int serial, in android.hardware.radio.ims.EpsFallbackReason reason);
   oneway void setResponseFunctions(in android.hardware.radio.ims.IRadioImsResponse radioImsResponse, in android.hardware.radio.ims.IRadioImsIndication radioImsIndication);
   oneway void sendAnbrQuery(int serial, android.hardware.radio.ims.ImsStreamType mediaType, android.hardware.radio.ims.ImsStreamDirection direction, int bitsPerSecond);
 }
diff --git a/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioImsResponse.aidl b/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioImsResponse.aidl
index 6f6b446..d4fd23f 100644
--- a/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioImsResponse.aidl
+++ b/radio/aidl/aidl_api/android.hardware.radio.ims/current/android/hardware/radio/ims/IRadioImsResponse.aidl
@@ -38,5 +38,6 @@
   oneway void updateImsRegistrationInfoResponse(in android.hardware.radio.RadioResponseInfo info);
   oneway void startImsTrafficResponse(in android.hardware.radio.RadioResponseInfo info, in @nullable android.hardware.radio.ims.ConnectionFailureInfo failureInfo);
   oneway void stopImsTrafficResponse(in android.hardware.radio.RadioResponseInfo info);
+  oneway void triggerEpsFallbackResponse(in android.hardware.radio.RadioResponseInfo info);
   oneway void sendAnbrQueryResponse(in android.hardware.radio.RadioResponseInfo info);
 }
diff --git a/radio/aidl/android/hardware/radio/ims/EpsFallbackReason.aidl b/radio/aidl/android/hardware/radio/ims/EpsFallbackReason.aidl
new file mode 100644
index 0000000..670638b
--- /dev/null
+++ b/radio/aidl/android/hardware/radio/ims/EpsFallbackReason.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"),
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.radio.ims;
+
+@VintfStability
+@JavaDerive(toString=true)
+@Backing(type="int")
+enum EpsFallbackReason {
+    /**
+     * If VoNR is not supported and EPS fallback is not triggered by network then UE initiated EPS
+     * fallback would be triggered by IMS stack with this reason. The modem shall locally release
+     * the 5G NR SA RRC connection and acquire the LTE network and perform a tracking area update
+     * procedure. After the EPS fallback procedure is completed, the call setup for voice will
+     * be established.
+     */
+    NO_NETWORK_TRIGGER = 1,
+
+    /**
+     * If the UE doesn't receive any response for SIP INVITE within a certain time in 5G NR SA,
+     * UE initiated EPS fallback will be triggered with this reason. The modem shall reset its data
+     * buffer of IMS PDUs to prevent the ghost call. After the EPS fallback procedure is completed,
+     * the VoLTE call will be established.
+     */
+    NO_NETWORK_RESPONSE = 2,
+}
diff --git a/radio/aidl/android/hardware/radio/ims/IRadioIms.aidl b/radio/aidl/android/hardware/radio/ims/IRadioIms.aidl
index 26f0337..e9796f4 100644
--- a/radio/aidl/android/hardware/radio/ims/IRadioIms.aidl
+++ b/radio/aidl/android/hardware/radio/ims/IRadioIms.aidl
@@ -17,6 +17,7 @@
 package android.hardware.radio.ims;
 
 import android.hardware.radio.AccessNetwork;
+import android.hardware.radio.ims.EpsFallbackReason;
 import android.hardware.radio.ims.ImsRegistration;
 import android.hardware.radio.ims.ImsStreamDirection;
 import android.hardware.radio.ims.ImsTrafficType;
@@ -103,6 +104,17 @@
     void stopImsTraffic(int serial, in String token);
 
     /**
+     * Triggers the UE initiated EPS fallback when a MO voice call failed to establish on 5G NR
+     * network and network didn't initiate a fallback.
+     *
+     * @param serial Serial number of request
+     * @param reason Specifies the reason that causes EPS fallback
+     *
+     * Response function is IRadioImsResponse.triggerEpsFallbackResponse()
+     */
+    void triggerEpsFallback(int serial, in EpsFallbackReason reason);
+
+    /**
      * Set response functions for IMS radio requests and indications.
      *
      * @param radioImsResponse Object containing response functions
diff --git a/radio/aidl/android/hardware/radio/ims/IRadioImsResponse.aidl b/radio/aidl/android/hardware/radio/ims/IRadioImsResponse.aidl
index f15b422..351e748 100644
--- a/radio/aidl/android/hardware/radio/ims/IRadioImsResponse.aidl
+++ b/radio/aidl/android/hardware/radio/ims/IRadioImsResponse.aidl
@@ -110,5 +110,22 @@
      *   RadioError:REQUEST_NOT_SUPPORTED
      *   RadioError:NO_RESOURCES
      */
+    void triggerEpsFallbackResponse(in RadioResponseInfo info);
+
+    /**
+     * @param info Response info struct containing response type, serial no. and error
+     *
+     * Valid errors returned:
+     *   RadioError:NONE
+     *   RadioError:RADIO_NOT_AVAILABLE
+     *   RadioError:INVALID_STATE
+     *   RadioError:NO_MEMORY
+     *   RadioError:SYSTEM_ERR
+     *   RadioError:MODEM_ERR
+     *   RadioError:INTERNAL_ERR
+     *   RadioError:INVALID_ARGUMENTS
+     *   RadioError:REQUEST_NOT_SUPPORTED
+     *   RadioError:NO_RESOURCES
+     */
     void sendAnbrQueryResponse(in RadioResponseInfo info);
 }
diff --git a/radio/aidl/vts/radio_ims_response.cpp b/radio/aidl/vts/radio_ims_response.cpp
index 7a90ebd..62912ea 100644
--- a/radio/aidl/vts/radio_ims_response.cpp
+++ b/radio/aidl/vts/radio_ims_response.cpp
@@ -45,6 +45,12 @@
     return ndk::ScopedAStatus::ok();
 }
 
+ndk::ScopedAStatus RadioImsResponse::triggerEpsFallbackResponse(const RadioResponseInfo& info) {
+    rspInfo = info;
+    parent_ims.notify(info.serial);
+    return ndk::ScopedAStatus::ok();
+}
+
 ndk::ScopedAStatus RadioImsResponse::sendAnbrQueryResponse(const RadioResponseInfo& info) {
     rspInfo = info;
     parent_ims.notify(info.serial);
diff --git a/radio/aidl/vts/radio_ims_test.cpp b/radio/aidl/vts/radio_ims_test.cpp
index d3bdd4b..52912c1 100644
--- a/radio/aidl/vts/radio_ims_test.cpp
+++ b/radio/aidl/vts/radio_ims_test.cpp
@@ -164,6 +164,32 @@
 }
 
 /*
+ * Test IRadioIms.triggerEpsFallback() for the response returned.
+ */
+TEST_P(RadioImsTest, triggerEpsFallback) {
+    if (!deviceSupportsFeature(FEATURE_TELEPHONY_IMS)) {
+        ALOGI("Skipping triggerEpsFallback because ims is not supported in device");
+        return;
+    } else {
+        ALOGI("Running triggerEpsFallback because ims is supported in device");
+    }
+
+    serial = GetRandomSerialNumber();
+
+    ndk::ScopedAStatus res =
+            radio_ims->triggerEpsFallback(serial, EpsFallbackReason::NO_NETWORK_TRIGGER);
+    ASSERT_OK(res);
+    EXPECT_EQ(std::cv_status::no_timeout, wait());
+    EXPECT_EQ(RadioResponseType::SOLICITED, radioRsp_ims->rspInfo.type);
+    EXPECT_EQ(serial, radioRsp_ims->rspInfo.serial);
+
+    ALOGI("triggerEpsFallback, rspInfo.error = %s\n",
+              toString(radioRsp_ims->rspInfo.error).c_str());
+
+    verifyError(radioRsp_ims->rspInfo.error);
+}
+
+/*
  * Test IRadioIms.sendAnbrQuery() for the response returned.
  */
 TEST_P(RadioImsTest, sendAnbrQuery) {
diff --git a/radio/aidl/vts/radio_ims_utils.h b/radio/aidl/vts/radio_ims_utils.h
index c9ecf4a..bf5684d 100644
--- a/radio/aidl/vts/radio_ims_utils.h
+++ b/radio/aidl/vts/radio_ims_utils.h
@@ -48,6 +48,8 @@
 
     virtual ndk::ScopedAStatus stopImsTrafficResponse(const RadioResponseInfo& info) override;
 
+    virtual ndk::ScopedAStatus triggerEpsFallbackResponse(const RadioResponseInfo& info) override;
+
     virtual ndk::ScopedAStatus sendAnbrQueryResponse(const RadioResponseInfo& info) override;
 };