diff --git a/SignalServiceKit/src/Account/TSAccountManager.h b/SignalServiceKit/src/Account/TSAccountManager.h
index 50e0d75cf..18e1446a2 100644
--- a/SignalServiceKit/src/Account/TSAccountManager.h
+++ b/SignalServiceKit/src/Account/TSAccountManager.h
@@ -9,6 +9,7 @@ NS_ASSUME_NONNULL_BEGIN
 extern NSString *const TSRegistrationErrorDomain;
 extern NSString *const TSRegistrationErrorUserInfoHTTPStatus;
 extern NSString *const RegistrationStateDidChangeNotification;
+extern NSString *const DeregistrationStateDidChangeNotification;
 extern NSString *const kNSNotificationName_LocalNumberDidChange;
 
 @class OWSPrimaryStorage;
@@ -116,6 +117,12 @@ extern NSString *const kNSNotificationName_LocalNumberDidChange;
 
 + (void)unregisterTextSecureWithSuccess:(void (^)(void))success failure:(void (^)(NSError *error))failureBlock;
 
+#pragma mark - Deregistration
+
+// De-registration reflects whether or not the service has received a 403
+- (BOOL)isDeregistered;
+- (void)setIsDeregistered:(BOOL)isDeregistered;
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Account/TSAccountManager.m b/SignalServiceKit/src/Account/TSAccountManager.m
index 1972c4b74..049459c69 100644
--- a/SignalServiceKit/src/Account/TSAccountManager.m
+++ b/SignalServiceKit/src/Account/TSAccountManager.m
@@ -23,9 +23,11 @@ NS_ASSUME_NONNULL_BEGIN
 NSString *const TSRegistrationErrorDomain = @"TSRegistrationErrorDomain";
 NSString *const TSRegistrationErrorUserInfoHTTPStatus = @"TSHTTPStatus";
 NSString *const RegistrationStateDidChangeNotification = @"RegistrationStateDidChangeNotification";
+NSString *const DeregistrationStateDidChangeNotification = @"DeregistrationStateDidChangeNotification";
 NSString *const kNSNotificationName_LocalNumberDidChange = @"kNSNotificationName_LocalNumberDidChange";
 
 NSString *const TSAccountManager_RegisteredNumberKey = @"TSStorageRegisteredNumberKey";
+NSString *const TSAccountManager_IsDeregisteredKey = @"TSAccountManager_IsDeregisteredKey";
 NSString *const TSAccountManager_LocalRegistrationIdKey = @"TSStorageLocalRegistrationId";
 
 NSString *const TSAccountManager_UserAccountCollection = @"TSStorageUserAccountCollection";
@@ -44,6 +46,8 @@ NSString *const TSAccountManager_ServerSignalingKey = @"TSStorageServerSignaling
 @property (nonatomic, nullable) NSString *cachedLocalNumber;
 @property (nonatomic, readonly) YapDatabaseConnection *dbConnection;
 
+@property (nonatomic, nullable) NSNumber *cachedIsDeregistered;
+
 @end
 
 #pragma mark -
@@ -108,6 +112,7 @@ NSString *const TSAccountManager_ServerSignalingKey = @"TSStorageServerSignaling
         _isRegistered = NO;
         _cachedLocalNumber = nil;
         _phoneNumberAwaitingVerification = nil;
+        _cachedIsDeregistered = nil;
         [self.dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
             [transaction removeAllObjectsInCollection:TSAccountManager_UserAccountCollection];
 
@@ -152,6 +157,7 @@ NSString *const TSAccountManager_ServerSignalingKey = @"TSStorageServerSignaling
     // Warm these cached values.
     [self isRegistered];
     [self localNumber];
+    [self isDeregistered];
 }
 
 + (nullable NSString *)localNumber
@@ -524,6 +530,47 @@ NSString *const TSAccountManager_ServerSignalingKey = @"TSStorageServerSignaling
     }
 }
 
+#pragma mark - Deregistration
+
+- (BOOL)isDeregistered
+{
+    // Cache this since we access this a lot, and once set it will not change.
+    @synchronized(self) {
+        if (self.cachedIsDeregistered == nil) {
+            self.cachedIsDeregistered = @([self.dbConnection boolForKey:TSAccountManager_IsDeregisteredKey
+                                                           inCollection:TSAccountManager_UserAccountCollection
+                                                           defaultValue:NO]);
+        }
+    }
+
+    OWSAssert(self.cachedIsDeregistered);
+    return self.cachedIsDeregistered.boolValue;
+}
+
+- (void)setIsDeregistered:(BOOL)isDeregistered
+{
+    @synchronized(self) {
+        if (self.cachedIsDeregistered && self.cachedIsDeregistered.boolValue == isDeregistered))
+            {
+                return;
+            }
+
+        DDLogWarn(@"%@ isDeregistered: %d", self.logTag, isDeregistered);
+
+        self.cachedIsDeregistered == @(isDeregistered);
+    }
+
+    [self.dbConnection asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+        [transaction setValue:@(isDeregistered)
+                       forKey:TSAccountManager_IsDeregisteredKey
+                 inCollection:TSAccountManager_UserAccountCollection];
+    }];
+
+    [[NSNotificationCenter defaultCenter] postNotificationNameAsync:DeregistrationStateDidChangeNotification
+                                                             object:nil
+                                                           userInfo:nil];
+}
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Network/API/TSNetworkManager.m b/SignalServiceKit/src/Network/API/TSNetworkManager.m
index 4d0d5adba..6e00e038f 100644
--- a/SignalServiceKit/src/Network/API/TSNetworkManager.m
+++ b/SignalServiceKit/src/Network/API/TSNetworkManager.m
@@ -87,6 +87,9 @@ typedef void (^failureBlock)(NSURLSessionDataTask *task, NSError *error);
     // TODO: Remove this logging when the call connection issues have been resolved.
     TSNetworkManagerSuccess success = ^(NSURLSessionDataTask *task, _Nullable id responseObject) {
         DDLogInfo(@"%@ request succeeded : %@", self.logTag, request);
+
+        [TSAccountManager.sharedInstance setIsDeregistered:NO];
+
         successBlock(task, responseObject);
     };
     TSNetworkManagerFailure failure = [TSNetworkManager errorPrettifyingForFailureBlock:failureBlock request:request];
@@ -166,6 +169,9 @@ typedef void (^failureBlock)(NSURLSessionDataTask *task, NSError *error);
           }
           case 400: {
               DDLogError(@"The request contains an invalid parameter : %@, %@", networkError.debugDescription, request);
+
+              [TSAccountManager.sharedInstance setIsDeregistered:YES];
+
               failureBlock(task, error);
               break;
           }
diff --git a/SignalServiceKit/src/Network/WebSockets/TSSocketManager.m b/SignalServiceKit/src/Network/WebSockets/TSSocketManager.m
index de4c6c0ba..064bbdae4 100644
--- a/SignalServiceKit/src/Network/WebSockets/TSSocketManager.m
+++ b/SignalServiceKit/src/Network/WebSockets/TSSocketManager.m
@@ -612,8 +612,14 @@ NSString *const kNSNotification_SocketManagerStateDidChange = @"kNSNotification_
         BOOL hasSuccessStatus = 200 <= responseStatus && responseStatus <= 299;
         BOOL didSucceed = hasSuccessStatus && hasValidResponse;
         if (didSucceed) {
+            [TSAccountManager.sharedInstance setIsDeregistered:NO];
+
             [socketMessage didSucceedWithResponseObject:responseObject];
         } else {
+            if (responseStatus == 403) {
+                [TSAccountManager.sharedInstance setIsDeregistered:YES];
+            }
+
             NSError *error = OWSErrorWithCodeDescription(OWSErrorCodeMessageResponseFailed,
                 NSLocalizedString(
                     @"ERROR_DESCRIPTION_RESPONSE_FAILED", @"Error indicating that a socket response failed."));