diff --git a/app/assets/javascripts/app/form-field-format.js b/app/assets/javascripts/app/form-field-format.js
index 308d63cf687..f00ec070241 100644
--- a/app/assets/javascripts/app/form-field-format.js
+++ b/app/assets/javascripts/app/form-field-format.js
@@ -1,5 +1,6 @@
-import { PhoneFormatter, SocialSecurityNumberFormatter, TextField } from 'field-kit';
+import { SocialSecurityNumberFormatter, TextField } from 'field-kit';
 import DateFormatter from './modules/date-formatter';
+import InternationalPhoneFormatter from './modules/international-phone-formatter';
 import NumericFormatter from './modules/numeric-formatter';
 import PersonalKeyFormatter from './modules/personal-key-formatter';
 import ZipCodeFormatter from './modules/zip-code-formatter';
@@ -13,7 +14,7 @@ function formatForm() {
     ['.home_equity_line', new NumericFormatter()],
     ['.mfa', new NumericFormatter()],
     ['.mortgage', new NumericFormatter()],
-    ['.phone', new PhoneFormatter()],
+    ['.phone', new InternationalPhoneFormatter()],
     ['.personal-key', new PersonalKeyFormatter()],
     ['.ssn', new SocialSecurityNumberFormatter()],
     ['.zipcode', new ZipCodeFormatter()],
diff --git a/app/assets/javascripts/app/modules/international-phone-formatter.js b/app/assets/javascripts/app/modules/international-phone-formatter.js
new file mode 100644
index 00000000000..2b3ee0b47db
--- /dev/null
+++ b/app/assets/javascripts/app/modules/international-phone-formatter.js
@@ -0,0 +1,69 @@
+import { Formatter } from 'field-kit';
+import { asYouType as AsYouType } from 'libphonenumber-js';
+
+const fixCountryCodeSpacing = (text, countryCode) => {
+  // If the text is `+123456`, make it `+123 456`
+  if (text[countryCode.length + 1] !== ' ') {
+    return text.replace(`+${countryCode}`, `+${countryCode} `);
+  }
+  return text;
+};
+
+const getFormattedTextData = (text) => {
+  if (text === '1') {
+    text = '+1';
+  }
+
+  const asYouType = new AsYouType('US');
+  let formattedText = asYouType.input(text);
+  const countryCode = asYouType.country_phone_code;
+
+  if (asYouType.country_phone_code) {
+    formattedText = fixCountryCodeSpacing(formattedText, countryCode);
+  }
+
+  return {
+    text: formattedText,
+    template: asYouType.template,
+    countryCode,
+  };
+};
+
+const cursorPosition = (formattedTextData) => {
+  // If the text is `(23 )` the cursor goes after the 3
+  const match = formattedTextData.text.match(/\d[^\d]*$/);
+  if (match) {
+    return match.index + 1;
+  }
+  return formattedTextData.text.length + 1;
+};
+
+class InternationalPhoneFormatter extends Formatter {
+  format(text) {
+    const formattedTextData = getFormattedTextData(text);
+    return super.format(formattedTextData.text);
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  parse(text) {
+    return text.replace(/[^\d+]/g, '');
+  }
+
+  isChangeValid(change, error) {
+    const formattedTextData = getFormattedTextData(change.proposed.text);
+    const previousFormattedTextData = getFormattedTextData(change.current.text);
+
+    if (previousFormattedTextData.template &&
+      !formattedTextData.template &&
+      change.inserted.text.length === 1
+    ) {
+      return false;
+    }
+
+    change.proposed.text = formattedTextData.text;
+    change.proposed.selectedRange.start = cursorPosition(formattedTextData);
+    return super.isChangeValid(change, error);
+  }
+}
+
+export default InternationalPhoneFormatter;
diff --git a/app/assets/javascripts/app/phone-internationalization.js b/app/assets/javascripts/app/phone-internationalization.js
index 9e985a169c3..af3e4724a33 100644
--- a/app/assets/javascripts/app/phone-internationalization.js
+++ b/app/assets/javascripts/app/phone-internationalization.js
@@ -1,5 +1,7 @@
 import { PhoneFormatter } from 'field-kit';
 
+const INTERNATIONAL_CODE_REGEX = /^\+(\d+) |^1 /;
+
 const I18n = window.LoginGov.I18n;
 const phoneFormatter = new PhoneFormatter();
 
@@ -18,7 +20,7 @@ const areaCodeFromUSPhone = (phone) => {
 };
 
 const selectedInternationCodeOption = () => {
-  const dropdown = document.querySelector('#two_factor_setup_form_international_code');
+  const dropdown = document.querySelector('[data-international-phone-form] .international-code');
   return dropdown.item(dropdown.selectedIndex);
 };
 
@@ -50,9 +52,14 @@ const unsupportedPhoneOTPDeliveryWarningMessage = (phone) => {
 };
 
 const updateOTPDeliveryMethods = () => {
-  const phoneInput = document.querySelector('#two_factor_setup_form_phone');
   const phoneRadio = document.querySelector('#two_factor_setup_form_otp_delivery_preference_voice');
   const smsRadio = document.querySelector('#two_factor_setup_form_otp_delivery_preference_sms');
+
+  if (!phoneRadio || !smsRadio) {
+    return;
+  }
+
+  const phoneInput = document.querySelector('[data-international-phone-form] .phone');
   const phoneLabel = phoneRadio.parentNode.parentNode;
   const deliveryMethodHint = document.querySelector('#otp_delivery_preference_instruction');
   const optPhoneLabelInfo = document.querySelector('#otp_phone_label_info');
@@ -74,14 +81,56 @@ const updateOTPDeliveryMethods = () => {
   }
 };
 
+const internationalCodeFromPhone = (phone) => {
+  const match = phone.match(INTERNATIONAL_CODE_REGEX);
+  if (match) {
+    return match[1] || match[2];
+  }
+  return '1';
+};
+
+const updateInternationalCodeSelection = () => {
+  const phoneInput = document.querySelector('[data-international-phone-form] .phone');
+  const phone = phoneInput.value;
+  const internationalCode = internationalCodeFromPhone(phone);
+  const option = document.querySelector(`[data-country-code='${internationalCode}']`);
+  if (option) {
+    const dropdown = document.querySelector('[data-international-phone-form] .international-code');
+    dropdown.value = option.value;
+  }
+};
+
+const updateInternationalCodeInPhone = (phone, newCode) => {
+  if (phone.match(/^\+[^d+]$/)) {
+    phone = phone.replace(/^\+[^d+]$/, '');
+  }
+  if (phone.match(INTERNATIONAL_CODE_REGEX)) {
+    return phone.replace(INTERNATIONAL_CODE_REGEX, `+${newCode} `);
+  }
+  return `+${newCode} ${phone}`;
+};
+
+const updateInternationalCodeInput = () => {
+  const phoneInput = document.querySelector('[data-international-phone-form] .phone');
+  const phone = phoneInput.value;
+  const inputInternationalCode = internationalCodeFromPhone(phone);
+  const selectedInternationalCode = selectedInternationCodeOption().dataset.countryCode;
+
+  if (inputInternationalCode !== selectedInternationalCode) {
+    phoneInput.value = updateInternationalCodeInPhone(phone, selectedInternationalCode);
+  }
+};
+
 document.addEventListener('DOMContentLoaded', () => {
-  const phoneInput = document.querySelector('#two_factor_setup_form_phone');
-  const codeInput = document.querySelector('#two_factor_setup_form_international_code');
+  const phoneInput = document.querySelector('[data-international-phone-form] .phone');
+  const codeInput = document.querySelector('[data-international-phone-form] .international-code');
   if (phoneInput) {
     phoneInput.addEventListener('keyup', updateOTPDeliveryMethods);
+    phoneInput.addEventListener('keyup', updateInternationalCodeSelection);
   }
   if (codeInput) {
     codeInput.addEventListener('change', updateOTPDeliveryMethods);
+    codeInput.addEventListener('change', updateInternationalCodeInput);
     updateOTPDeliveryMethods();
   }
 });
diff --git a/app/views/users/phones/edit.html.slim b/app/views/users/phones/edit.html.slim
index e2c3498a1fd..73ba00505a9 100644
--- a/app/views/users/phones/edit.html.slim
+++ b/app/views/users/phones/edit.html.slim
@@ -2,11 +2,15 @@
 
 
 h1.h3.my0 = t('headings.edit_info.phone')
-= simple_form_for(@update_user_phone_form, url: manage_phone_path,
+= simple_form_for(@update_user_phone_form,
+    data: { unsupported_area_codes: @unsupported_area_codes,
+      international_phone_form: true },
+    url: manage_phone_path,
     html: { autocomplete: 'off', method: :put, role: 'form' }) do |f|
   = f.input :international_code,
         collection: international_phone_codes,
-        include_blank: false
+        include_blank: false,
+        input_html: { class: 'international-code' }
   = f.input :phone, as: :tel, required: true, input_html: { class: 'phone', value: nil },
     label: t('account.index.phone')
   = f.button :submit, t('forms.buttons.submit.confirm_change'), class: 'mt2'
diff --git a/app/views/users/two_factor_authentication_setup/index.html.slim b/app/views/users/two_factor_authentication_setup/index.html.slim
index 27b0fc87370..2a86ed90b15 100644
--- a/app/views/users/two_factor_authentication_setup/index.html.slim
+++ b/app/views/users/two_factor_authentication_setup/index.html.slim
@@ -5,14 +5,16 @@ p.mt-tiny.mb0
   = t('devise.two_factor_authentication.otp_setup_html')
 = simple_form_for(@two_factor_setup_form,
     html: { autocomplete: 'off', role: 'form' },
-    data: { unsupported_area_codes: @unsupported_area_codes },
+    data: { unsupported_area_codes: @unsupported_area_codes,
+      international_phone_form: true },
     method: :patch,
     url: phone_setup_path) do |f|
   .clearfix
     .sm-col.sm-col-8
       = f.input :international_code,
         collection: international_phone_codes,
-        include_blank: false
+        include_blank: false,
+        input_html: { class: 'international-code' }
   = f.label :phone, class: 'block'
     strong.left = t('devise.two_factor_authentication.otp_phone_label')
     span#otp_phone_label_info.ml1.italic
diff --git a/package.json b/package.json
index a0f99141f21..5e216e62d1e 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "field-kit": "^2.1.0",
     "focus-trap": "^2.3.0",
     "hint.css": "^2.3.2",
+    "libphonenumber-js": "^0.4.23",
     "normalize.css": "^4.2.0",
     "sinon": "^1.17.7",
     "zxcvbn": "^4.4.2"
diff --git a/spec/features/idv/phone_spec.rb b/spec/features/idv/phone_spec.rb
index 666eb327173..2d824ef3117 100644
--- a/spec/features/idv/phone_spec.rb
+++ b/spec/features/idv/phone_spec.rb
@@ -79,7 +79,7 @@
     fill_in 'Phone', with: ''
     find('#idv_phone_form_phone').native.send_keys('abcd1234')
 
-    expect(find('#idv_phone_form_phone').value).to eq '1 (234) '
+    expect(find('#idv_phone_form_phone').value).to eq '+1 234'
   end
 
   def complete_idv_profile_with_phone(phone)
diff --git a/spec/features/two_factor_authentication/sign_in_spec.rb b/spec/features/two_factor_authentication/sign_in_spec.rb
index 01c6f7fbc74..7ce7aff8dd1 100644
--- a/spec/features/two_factor_authentication/sign_in_spec.rb
+++ b/spec/features/two_factor_authentication/sign_in_spec.rb
@@ -92,7 +92,7 @@
       scenario 'disables the phone option and displays a warning with js', :js do
         sign_in_before_2fa
         select 'Turkey +90', from: 'International code'
-        fill_in 'Phone', with: '555-555-5000'
+        fill_in 'Phone', with: '+90 312 213 29 65'
         phone_radio_button = page.find(
           '#two_factor_setup_form_otp_delivery_preference_voice',
           visible: :all
@@ -112,6 +112,23 @@
         )
         expect(phone_radio_button).to_not be_disabled
       end
+
+      scenario 'updates international code as user types', :js do
+        sign_in_before_2fa
+        fill_in 'Phone', with: '+81 54 354 3643'
+
+        expect(page.find('#two_factor_setup_form_international_code').value).to eq 'JP'
+
+        fill_in 'Phone', with: '5376'
+        select 'Morocco +212', from: 'International code'
+
+        expect(find('#two_factor_setup_form_phone').value).to eq '+212 5376'
+
+        fill_in 'Phone', with: '54354'
+        select 'Japan +81', from: 'International code'
+
+        expect(find('#two_factor_setup_form_phone').value).to include '+81'
+      end
     end
   end
 
diff --git a/spec/features/users/user_edit_spec.rb b/spec/features/users/user_edit_spec.rb
index 41041acce6c..90810805be6 100644
--- a/spec/features/users/user_edit_spec.rb
+++ b/spec/features/users/user_edit_spec.rb
@@ -1,23 +1,47 @@
 require 'rails_helper'
 
 feature 'User edit' do
-  scenario 'user sees error message if form is submitted without email', js: true, idv_job: true do
-    sign_in_and_2fa_user
+  context 'editing email' do
+    before do
+      sign_in_and_2fa_user
+      visit manage_email_path
+    end
 
-    visit manage_email_path
-    fill_in 'Email', with: ''
-    click_button 'Update'
+    scenario 'user sees error message if form is submitted without email', :js, idv_job: true do
+      fill_in 'Email', with: ''
+      click_button 'Update'
 
-    expect(page).to have_content t('valid_email.validations.email.invalid')
+      expect(page).to have_content t('valid_email.validations.email.invalid')
+    end
   end
 
-  scenario 'user sees error message if form is submitted without phone number', js: true do
-    sign_in_and_2fa_user
+  context 'editing 2FA phone number' do
+    before do
+      sign_in_and_2fa_user
+      visit manage_phone_path
+    end
 
-    visit manage_phone_path
-    fill_in 'Phone', with: ''
-    click_button t('forms.buttons.submit.confirm_change')
+    scenario 'user sees error message if form is submitted without phone number', js: true do
+      fill_in 'Phone', with: ''
+      click_button t('forms.buttons.submit.confirm_change')
 
-    expect(page).to have_content t('errors.messages.improbable_phone')
+      expect(page).to have_content t('errors.messages.improbable_phone')
+    end
+
+    scenario 'updates international code as user types', :js do
+      fill_in 'Phone', with: '+81 54 354 3643'
+
+      expect(page.find('#update_user_phone_form_international_code').value).to eq 'JP'
+
+      fill_in 'Phone', with: '5376'
+      select 'Morocco +212', from: 'International code'
+
+      expect(find('#update_user_phone_form_phone').value).to eq '+212 5376'
+
+      fill_in 'Phone', with: '54354'
+      select 'Japan +81', from: 'International code'
+
+      expect(find('#update_user_phone_form_phone').value).to include '+81'
+    end
   end
 end