diff --git a/Signal/src/ViewControllers/Registration/OnboardingPhoneNumberViewController.swift b/Signal/src/ViewControllers/Registration/OnboardingPhoneNumberViewController.swift
index 7f9d8a7a7..bd521d2db 100644
--- a/Signal/src/ViewControllers/Registration/OnboardingPhoneNumberViewController.swift
+++ b/Signal/src/ViewControllers/Registration/OnboardingPhoneNumberViewController.swift
@@ -103,7 +103,7 @@ public class OnboardingPhoneNumberViewController: OnboardingBaseViewController {
         let validationWarningRow = UIView()
         validationWarningRow.addSubview(validationWarningLabel)
         validationWarningLabel.autoPinHeightToSuperview()
-        validationWarningLabel.autoPinEdge(toSuperviewEdge: .leading)
+        validationWarningLabel.autoPinEdge(toSuperviewEdge: .trailing)
 
         let nextButton = self.button(title: NSLocalizedString("BUTTON_NEXT",
                                                                 comment: "Label for the 'next' button."),
@@ -216,6 +216,9 @@ public class OnboardingPhoneNumberViewController: OnboardingBaseViewController {
         phoneNumberTextField.isEnabled = false
 
         updateViewState()
+
+        // Trigger the formatting logic with a no-op edit.
+        _ = textField(phoneNumberTextField, shouldChangeCharactersIn: NSRange(location: 0, length: 0), replacementString: "")
     }
 
     // MARK: -
@@ -250,6 +253,9 @@ public class OnboardingPhoneNumberViewController: OnboardingBaseViewController {
         }
 
         updateViewState()
+
+        // Trigger the formatting logic with a no-op edit.
+        _ = textField(phoneNumberTextField, shouldChangeCharactersIn: NSRange(location: 0, length: 0), replacementString: "")
     }
 
     private func updateViewState() {
@@ -365,8 +371,7 @@ public class OnboardingPhoneNumberViewController: OnboardingBaseViewController {
 
 extension OnboardingPhoneNumberViewController: UITextFieldDelegate {
     public func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
-        // TODO: Fix auto-format of phone numbers.
-        ViewControllerUtils.phoneNumber(textField, shouldChangeCharactersIn: range, replacementString: string, countryCode: countryCode)
+        ViewControllerUtils.phoneNumber(textField, shouldChangeCharactersIn: range, replacementString: string, callingCode: callingCode)
 
         isPhoneNumberInvalid = false
         updateValidationWarnings()
diff --git a/Signal/src/ViewControllers/Registration/RegistrationViewController.m b/Signal/src/ViewControllers/Registration/RegistrationViewController.m
index 823d7385f..2a2a0d914 100644
--- a/Signal/src/ViewControllers/Registration/RegistrationViewController.m
+++ b/Signal/src/ViewControllers/Registration/RegistrationViewController.m
@@ -552,7 +552,7 @@ NSString *const kKeychainKey_LastRegisteredPhoneNumber = @"kKeychainKey_LastRegi
     [ViewControllerUtils phoneNumberTextField:textField
                 shouldChangeCharactersInRange:range
                             replacementString:insertionText
-                                  countryCode:_callingCode];
+                                  callingCode:_callingCode];
 
     return NO; // inform our caller that we took care of performing the change
 }
diff --git a/SignalMessaging/ViewControllers/SelectRecipientViewController.m b/SignalMessaging/ViewControllers/SelectRecipientViewController.m
index 01c06b2ce..006bd0c9c 100644
--- a/SignalMessaging/ViewControllers/SelectRecipientViewController.m
+++ b/SignalMessaging/ViewControllers/SelectRecipientViewController.m
@@ -423,7 +423,7 @@ NSString *const kSelectRecipientViewControllerCellIdentifier = @"kSelectRecipien
     [ViewControllerUtils phoneNumberTextField:textField
                 shouldChangeCharactersInRange:range
                             replacementString:insertionText
-                                  countryCode:_callingCode];
+                                  callingCode:_callingCode];
 
     [self updatePhoneNumberButtonEnabling];
 
diff --git a/SignalMessaging/ViewControllers/ViewControllerUtils.h b/SignalMessaging/ViewControllers/ViewControllerUtils.h
index 38b26561d..f027db313 100644
--- a/SignalMessaging/ViewControllers/ViewControllerUtils.h
+++ b/SignalMessaging/ViewControllers/ViewControllerUtils.h
@@ -17,10 +17,12 @@ extern NSString *const TappedStatusBarNotification;
 // This convenience function can be used to reformat the contents of
 // a phone number text field as the user modifies its text by typing,
 // pasting, etc.
+//
+// "callingCode" should be of the form: "+1".
 + (void)phoneNumberTextField:(UITextField *)textField
     shouldChangeCharactersInRange:(NSRange)range
                 replacementString:(NSString *)insertionText
-                      countryCode:(NSString *)countryCode;
+                      callingCode:(NSString *)callingCode;
 
 + (void)ows2FAPINTextField:(UITextField *)textField
     shouldChangeCharactersInRange:(NSRange)range
diff --git a/SignalMessaging/ViewControllers/ViewControllerUtils.m b/SignalMessaging/ViewControllers/ViewControllerUtils.m
index 441e3e797..96896f08a 100644
--- a/SignalMessaging/ViewControllers/ViewControllerUtils.m
+++ b/SignalMessaging/ViewControllers/ViewControllerUtils.m
@@ -21,20 +21,7 @@ const NSUInteger kMax2FAPinLength = 16;
 + (void)phoneNumberTextField:(UITextField *)textField
     shouldChangeCharactersInRange:(NSRange)range
                 replacementString:(NSString *)insertionText
-                      countryCode:(NSString *)countryCode
-{
-    return [self phoneNumberTextField:textField
-        shouldChangeCharactersInRange:range
-                    replacementString:insertionText
-                          countryCode:countryCode
-                               prefix:nil];
-}
-
-+ (void)phoneNumberTextField:(UITextField *)textField
-    shouldChangeCharactersInRange:(NSRange)range
-                replacementString:(NSString *)insertionText
-                      countryCode:(NSString *)countryCode
-                           prefix:(nullable NSString *)prefix
+                      callingCode:(NSString *)callingCode
 {
     // Phone numbers takes many forms.
     //
@@ -90,15 +77,15 @@ const NSUInteger kMax2FAPinLength = 16;
     // reformat the phone number, trying to keep the cursor beside the inserted or deleted digit
     NSUInteger cursorPositionAfterChange = MIN(left.length + center.length, textAfterChange.length);
 
-    NSString *textAfterReformat =
-        [PhoneNumber bestEffortFormatPartialUserSpecifiedTextToLookLikeAPhoneNumber:textAfterChange
-                                                     withSpecifiedCountryCodeString:countryCode];
+    NSString *textToFormat = textAfterChange;
+    NSString *formattedText = [PhoneNumber bestEffortFormatPartialUserSpecifiedTextToLookLikeAPhoneNumber:textToFormat
+                                                                           withSpecifiedCountryCodeString:callingCode];
     NSUInteger cursorPositionAfterReformat = [PhoneNumberUtil translateCursorPosition:cursorPositionAfterChange
-                                                                                 from:textAfterChange
-                                                                                   to:textAfterReformat
+                                                                                 from:textToFormat
+                                                                                   to:formattedText
                                                                     stickingRightward:isJustDeletion];
 
-    textField.text = textAfterReformat;
+    textField.text = formattedText;
     UITextPosition *pos =
         [textField positionFromPosition:textField.beginningOfDocument offset:(NSInteger)cursorPositionAfterReformat];
     [textField setSelectedTextRange:[textField textRangeFromPosition:pos toPosition:pos]];