diff --git a/signup-service/src/main/java/io/mosip/signup/dto/RegisterRequest.java b/signup-service/src/main/java/io/mosip/signup/dto/RegisterRequest.java
index 45a395a4..40ad7a9f 100644
--- a/signup-service/src/main/java/io/mosip/signup/dto/RegisterRequest.java
+++ b/signup-service/src/main/java/io/mosip/signup/dto/RegisterRequest.java
@@ -1,6 +1,7 @@
 package io.mosip.signup.dto;
 
 import io.mosip.signup.util.ErrorConstants;
+import io.mosip.signup.validator.Language;
 import io.mosip.signup.validator.Password;
 import io.mosip.signup.validator.Username;
 import lombok.Data;
@@ -26,5 +27,6 @@ public class RegisterRequest {
     @NotNull(message = ErrorConstants.INVALID_USERINFO)
     private @Valid UserInfoMap userInfo;
 
+    @Language(required = false)
     private String locale;
 }
diff --git a/signup-service/src/main/java/io/mosip/signup/dto/ResetPasswordRequest.java b/signup-service/src/main/java/io/mosip/signup/dto/ResetPasswordRequest.java
index c0976dfe..e5c19980 100644
--- a/signup-service/src/main/java/io/mosip/signup/dto/ResetPasswordRequest.java
+++ b/signup-service/src/main/java/io/mosip/signup/dto/ResetPasswordRequest.java
@@ -1,6 +1,7 @@
 package io.mosip.signup.dto;
 
 import io.mosip.signup.validator.Identifier;
+import io.mosip.signup.validator.Language;
 import io.mosip.signup.validator.Password;
 import lombok.Data;
 
@@ -13,5 +14,6 @@ public class ResetPasswordRequest {
     @Password
     private String password;
 
+    @Language(required = false)
     private String locale;
 }
diff --git a/signup-service/src/main/java/io/mosip/signup/services/RegistrationService.java b/signup-service/src/main/java/io/mosip/signup/services/RegistrationService.java
index 03812591..520cdc10 100644
--- a/signup-service/src/main/java/io/mosip/signup/services/RegistrationService.java
+++ b/signup-service/src/main/java/io/mosip/signup/services/RegistrationService.java
@@ -251,7 +251,9 @@ public RegisterResponse register(RegisterRequest registerRequest, String transac
         transaction.setRegistrationStatus(RegistrationStatus.PENDING);
         cacheUtilService.setStatusCheckTransaction(transactionId, transaction);
 
-        notificationHelper.sendSMSNotificationAsync(registerRequest.getUserInfo().getPhone(), registerRequest.getLocale(),
+        String locale = registerRequest.getLocale() == null ? transaction.getLocale() : registerRequest.getLocale();
+
+        notificationHelper.sendSMSNotificationAsync(registerRequest.getUserInfo().getPhone(), locale,
                         REGISTRATION_SMS_NOTIFICATION_TEMPLATE_KEY, null)
                 .thenAccept(notificationResponseRestResponseWrapper ->
                     log.debug(notificationLogging, notificationResponseRestResponseWrapper)
@@ -324,7 +326,9 @@ public RegistrationStatusResponse updatePassword(ResetPasswordRequest resetPassw
         transaction.setRegistrationStatus(RegistrationStatus.PENDING);
         cacheUtilService.setStatusCheckTransaction(transactionId, transaction);
 
-        notificationHelper.sendSMSNotificationAsync(resetPasswordRequest.getIdentifier(), resetPasswordRequest.getLocale(),
+        String locale = resetPasswordRequest.getLocale() == null ? transaction.getLocale() : resetPasswordRequest.getLocale();
+
+        notificationHelper.sendSMSNotificationAsync(resetPasswordRequest.getIdentifier(), locale,
                         FORGOT_PASSWORD_SMS_NOTIFICATION_TEMPLATE_KEY, null)
                 .thenAccept(notificationResponseRestResponseWrapper ->
                     log.debug(notificationLogging, notificationResponseRestResponseWrapper)
diff --git a/signup-service/src/test/java/io/mosip/signup/services/RegistrationServiceTest.java b/signup-service/src/test/java/io/mosip/signup/services/RegistrationServiceTest.java
index b324dbdf..ea282abd 100644
--- a/signup-service/src/test/java/io/mosip/signup/services/RegistrationServiceTest.java
+++ b/signup-service/src/test/java/io/mosip/signup/services/RegistrationServiceTest.java
@@ -838,6 +838,69 @@ public void register_thenPass() throws SignUpException {
         Assert.assertEquals("PENDING", registerResponse.getStatus());
     }
 
+    @Test
+    public void register_withNullLocale_thenPass() throws SignUpException {
+
+        UserInfoMap userInfo = new UserInfoMap();
+        userInfo.setPreferredLang("khm");
+        userInfo.setFullName(List.of(new LanguageTaggedValue("eng", "Panharith AN")));
+        userInfo.setPhone("+855219718732");
+
+        RegisterRequest registerRequest = new RegisterRequest();
+        registerRequest.setUserInfo(userInfo);
+        registerRequest.setUsername("+855219718732");
+        registerRequest.setPassword("123123");
+        registerRequest.setConsent("AGREE");
+        registerRequest.setLocale(null);
+
+        String mockTransactionID = "123456789";
+
+        RegistrationTransaction mockRegistrationTransaction = new RegistrationTransaction(userInfo.getPhone(), Purpose.REGISTRATION);
+        mockRegistrationTransaction.setChallengeHash("123456");
+        mockRegistrationTransaction.setIdentifier(userInfo.getPhone());
+
+        when(cacheUtilService.getChallengeVerifiedTransaction(mockTransactionID))
+                .thenReturn(mockRegistrationTransaction);
+
+        IdentityResponse identityResponse = new IdentityResponse();
+        identityResponse.setStatus("ACTIVATED");
+        UINResponse uinResponse = new UINResponse();
+        uinResponse.setUIN("mockUIN");
+        Password.PasswordHash passwordHash = new Password.PasswordHash();
+        passwordHash.setSalt("mockSalt");
+        passwordHash.setHashValue("mockHashValue");
+
+        RestResponseWrapper<IdentityResponse> mockRestResponseWrapperAddIdentityResponse = new RestResponseWrapper<IdentityResponse>();
+        mockRestResponseWrapperAddIdentityResponse.setResponse(identityResponse);
+        RestResponseWrapper<UINResponse> mockRestResponseWrapperUINResponse = new RestResponseWrapper<UINResponse>();
+        mockRestResponseWrapperUINResponse.setResponse(uinResponse);
+        RestResponseWrapper<Password.PasswordHash> mockRestResponseWrapperPasswordHash = new RestResponseWrapper<Password.PasswordHash>();
+        mockRestResponseWrapperPasswordHash.setResponse(passwordHash);
+
+        when(selfTokenRestTemplate.exchange(
+                eq(getUinEndpoint),
+                eq(HttpMethod.GET),
+                eq(null),
+                any(ParameterizedTypeReference.class))).thenReturn(new ResponseEntity<>(mockRestResponseWrapperUINResponse, HttpStatus.OK));
+        when(selfTokenRestTemplate.exchange(
+                eq(generateHashEndpoint),
+                eq(HttpMethod.POST),
+                any(HttpEntity.class),
+                any(ParameterizedTypeReference.class))).thenReturn(new ResponseEntity<>(mockRestResponseWrapperPasswordHash, HttpStatus.OK));
+        when(selfTokenRestTemplate.exchange(
+                eq(identityEndpoint),
+                eq(HttpMethod.POST),
+                any(HttpEntity.class),
+                any(ParameterizedTypeReference.class))).thenReturn(new ResponseEntity<>(mockRestResponseWrapperAddIdentityResponse, HttpStatus.OK));
+
+        when(notificationHelper.sendSMSNotificationAsync(any(), any(), any(), any()))
+                .thenReturn(new CompletableFuture<>());
+
+        RegisterResponse registerResponse = registrationService.register(registerRequest, mockTransactionID);
+        Assert.assertNotNull(registerResponse);
+        Assert.assertEquals("PENDING", registerResponse.getStatus());
+    }
+
     @Test
     public void register_whenUinEndpointResponseNullBody_throwGetUINFailed() throws SignUpException {
         String locale = "eng";
@@ -2020,6 +2083,53 @@ public void doUpdatePassword_thenSuccess() {
         Assert.assertEquals(RegistrationStatus.PENDING, registrationStatusResponse.getStatus());
     }
 
+    @Test
+    public void doUpdatePassword_withNullLocale_thenSuccess() {
+
+        String verifiedTransactionId = "VERIFIED_TRANSACTION_ID";
+        ResetPasswordRequest resetPasswordRequest = new ResetPasswordRequest();
+        resetPasswordRequest.setPassword("Password@2002");
+        resetPasswordRequest.setIdentifier("+85512345678");
+        resetPasswordRequest.setLocale(null);
+
+        RegistrationTransaction transaction = new RegistrationTransaction(resetPasswordRequest.getIdentifier(),
+                Purpose.RESET_PASSWORD);
+        transaction.setUin("mockUin");
+
+        Password.PasswordHash passwordHash = new Password.PasswordHash();
+        passwordHash.setSalt("mockSalt");
+        passwordHash.setHashValue("mockHashValue");
+        RestResponseWrapper<Password.PasswordHash> mockPasswordHashRestResponseWrapper = new RestResponseWrapper<>();
+        mockPasswordHashRestResponseWrapper.setResponse(passwordHash);
+
+        RestResponseWrapper<IdentityResponse> mockIdentityResponseRestResponseWrapper = new RestResponseWrapper<>();
+        IdentityResponse mockIdentityResponse = new IdentityResponse();
+        mockIdentityResponseRestResponseWrapper.setResponse(mockIdentityResponse);
+        mockIdentityResponse.setStatus(SignUpConstants.ACTIVATED);
+        mockIdentityResponseRestResponseWrapper.setErrors(new ArrayList<>());
+
+        when(cacheUtilService.getChallengeVerifiedTransaction(verifiedTransactionId)).thenReturn(transaction);
+        when(selfTokenRestTemplate.exchange(
+                eq(generateHashEndpoint),
+                eq(HttpMethod.POST),
+                any(HttpEntity.class),
+                any(ParameterizedTypeReference.class)))
+                .thenReturn(new ResponseEntity<>(mockPasswordHashRestResponseWrapper, HttpStatus.OK));
+        when(selfTokenRestTemplate.exchange(
+                eq(identityEndpoint),
+                eq(HttpMethod.PATCH),
+                any(HttpEntity.class),
+                any(ParameterizedTypeReference.class)))
+                .thenReturn(new ResponseEntity<>(mockIdentityResponseRestResponseWrapper, HttpStatus.OK));
+
+        when(notificationHelper.sendSMSNotificationAsync(any(), any(), any(), any()))
+                .thenReturn(new CompletableFuture<>());
+
+        RegistrationStatusResponse registrationStatusResponse = registrationService.updatePassword(resetPasswordRequest,
+                verifiedTransactionId);
+        Assert.assertEquals(RegistrationStatus.PENDING, registrationStatusResponse.getStatus());
+    }
+
     @Test
     public void doUpdatePassword_withInvalidTransaction_thenSuccess() {