diff --git a/Signal/src/ViewControllers/RegistrationViewController.h b/Signal/src/ViewControllers/RegistrationViewController.h
index 08f02f444..2c6bf9fdb 100644
--- a/Signal/src/ViewControllers/RegistrationViewController.h
+++ b/Signal/src/ViewControllers/RegistrationViewController.h
@@ -4,6 +4,10 @@
 
 #import <UIKit/UIKit.h>
 
-@interface RegistrationViewController : UIViewController <UITextFieldDelegate>
+NS_ASSUME_NONNULL_BEGIN
+
+@interface RegistrationViewController : UIViewController
 
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/Signal/src/ViewControllers/RegistrationViewController.m b/Signal/src/ViewControllers/RegistrationViewController.m
index 3e175387d..bdfbfe419 100644
--- a/Signal/src/ViewControllers/RegistrationViewController.m
+++ b/Signal/src/ViewControllers/RegistrationViewController.m
@@ -12,9 +12,20 @@
 #import "TSAccountManager.h"
 #import "UIView+OWS.h"
 #import "ViewControllerUtils.h"
+#import <SAMKeychain/SAMKeychain.h>
 
-@interface RegistrationViewController () <CountryCodeViewControllerDelegate>
+NS_ASSUME_NONNULL_BEGIN
 
+#ifdef DEBUG
+
+NSString *const kNSUserDefaultsKey_LastRegisteredCountryCode = @"kNSUserDefaultsKey_LastRegisteredCountryCode";
+NSString *const kNSUserDefaultsKey_LastRegisteredPhoneNumber = @"kNSUserDefaultsKey_LastRegisteredPhoneNumber";
+
+#endif
+
+@interface RegistrationViewController () <CountryCodeViewControllerDelegate, UITextFieldDelegate>
+
+@property (nonatomic) NSString *countryCode;
 @property (nonatomic) NSString *callingCode;
 
 @property (nonatomic) UILabel *countryCodeLabel;
@@ -194,7 +205,7 @@
                          ofView:separatorView2
                      withOffset:ScaleFromIPhone5To7Plus(12.f, 15.f)];
     [activateButton autoSetDimension:ALDimensionHeight toSize:47.f];
-    [activateButton addTarget:self action:@selector(sendCodeAction:) forControlEvents:UIControlEventTouchUpInside];
+    [activateButton addTarget:self action:@selector(sendCodeAction) forControlEvents:UIControlEventTouchUpInside];
 
     UIActivityIndicatorView *spinnerView =
         [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
@@ -237,6 +248,14 @@
 - (void)populateDefaultCountryNameAndCode {
     NSLocale *locale      = NSLocale.currentLocale;
     NSString *countryCode = [locale objectForKey:NSLocaleCountryCode];
+
+#ifdef DEBUG
+    if ([self lastRegisteredCountryCode].length > 0) {
+        countryCode = [self lastRegisteredCountryCode];
+    }
+    self.phoneNumberTextField.text = [self lastRegisteredPhoneNumber];
+#endif
+
     NSNumber *callingCode = [[PhoneNumberUtil sharedUtil].nbPhoneNumberUtil getCountryCodeForRegion:countryCode];
     NSString *countryName = [PhoneNumberUtil countryNameFromCountryCode:countryCode];
     [self updateCountryWithName:countryName
@@ -249,7 +268,12 @@
 - (void)updateCountryWithName:(NSString *)countryName
                   callingCode:(NSString *)callingCode
                   countryCode:(NSString *)countryCode {
+    OWSAssert([NSThread isMainThread]);
+    OWSAssert(countryName.length > 0);
+    OWSAssert(callingCode.length > 0);
+    OWSAssert(countryCode.length > 0);
 
+    _countryCode = countryCode;
     _callingCode = callingCode;
 
     NSString *title = [NSString stringWithFormat:@"%@ (%@)",
@@ -277,7 +301,7 @@
                    message:NSLocalizedString(@"EXISTING_USER_REGISTRATION_ALERT_BODY", @"during registration")];
 }
 
-- (void)sendCodeAction:(id)sender
+- (void)sendCodeAction
 {
     NSString *phoneNumberText =
         [_phoneNumberTextField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
@@ -290,6 +314,7 @@
                                @"Message of alert indicating that users needs to enter a phone number to register.")];
         return;
     }
+    NSString *countryCode = self.countryCode;
     NSString *phoneNumber = [NSString stringWithFormat:@"%@%@", _callingCode, phoneNumberText];
     PhoneNumber *localNumber = [PhoneNumber tryParsePhoneNumberFromUserSpecifiedText:phoneNumber];
     NSString *parsedPhoneNumber = localNumber.toE164;
@@ -314,6 +339,11 @@
 
             CodeVerificationViewController *vc = [CodeVerificationViewController new];
             [weakSelf.navigationController pushViewController:vc animated:YES];
+
+#ifdef DEBUG
+            [weakSelf setLastRegisteredCountryCode:countryCode];
+            [weakSelf setLastRegisteredPhoneNumber:phoneNumberText];
+#endif
         }
         failure:^(NSError *error) {
             if (error.code == 400) {
@@ -396,9 +426,54 @@
 }
 
 - (BOOL)textFieldShouldReturn:(UITextField *)textField {
-    [self sendCodeAction:nil];
+    [self sendCodeAction];
     [textField resignFirstResponder];
     return NO;
 }
 
+#pragma mark - Debug
+
+#ifdef DEBUG
+
+- (NSString *_Nullable)debugValueForKey:(NSString *)key
+{
+    OWSCAssert([NSThread isMainThread]);
+    OWSCAssert(key.length > 0);
+
+    return [[NSUserDefaults standardUserDefaults] stringForKey:key];
+}
+
+- (void)setDebugValue:(NSString *)value forKey:(NSString *)key
+{
+    OWSCAssert([NSThread isMainThread]);
+    OWSCAssert(key.length > 0);
+    OWSCAssert(value.length > 0);
+
+    [[NSUserDefaults standardUserDefaults] setValue:value forKey:key];
+}
+
+- (NSString *_Nullable)lastRegisteredCountryCode
+{
+    return [self debugValueForKey:kNSUserDefaultsKey_LastRegisteredCountryCode];
+}
+
+- (void)setLastRegisteredCountryCode:(NSString *)value
+{
+    [self setDebugValue:value forKey:kNSUserDefaultsKey_LastRegisteredCountryCode];
+}
+
+- (NSString *_Nullable)lastRegisteredPhoneNumber
+{
+    return [self debugValueForKey:kNSUserDefaultsKey_LastRegisteredPhoneNumber];
+}
+
+- (void)setLastRegisteredPhoneNumber:(NSString *)value
+{
+    [self setDebugValue:value forKey:kNSUserDefaultsKey_LastRegisteredPhoneNumber];
+}
+
+#endif
+
 @end
+
+NS_ASSUME_NONNULL_END