diff --git a/package.json b/package.json
index e3876b9ad2..c4b9f89d53 100644
--- a/package.json
+++ b/package.json
@@ -171,6 +171,7 @@
     "js-sha256": "^0.9.0",
     "jwt-decode": "^4.0.0",
     "lande": "^1.0.10",
+    "libphonenumber-js": "^1.12.30",
     "lodash.chunk": "^4.2.0",
     "lodash.debounce": "^4.0.8",
     "lodash.isequal": "^4.5.0",
diff --git a/src/components/InternationalPhoneCodeSelect.tsx b/src/components/InternationalPhoneCodeSelect.tsx
index f42f4a21a3..2a51e2ccff 100644
--- a/src/components/InternationalPhoneCodeSelect.tsx
+++ b/src/components/InternationalPhoneCodeSelect.tsx
@@ -4,6 +4,7 @@ import {msg} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
 
 import {
+  type CountryCode,
   getDefaultCountry,
   INTERNATIONAL_TELEPHONE_CODES,
 } from '#/lib/international-telephone-codes'
@@ -23,8 +24,8 @@ export function InternationalPhoneCodeSelect({
   value,
   onChange,
 }: {
-  value?: string
-  onChange: (value: string) => void
+  value?: CountryCode
+  onChange: (value: CountryCode) => void
 }) {
   const {_, i18n} = useLingui()
   const location = useGeolocation()
diff --git a/src/components/contacts/SyncContactsFlow.web.tsx b/src/components/contacts/SyncContactsFlow.web.tsx
new file mode 100644
index 0000000000..d40435f6fa
--- /dev/null
+++ b/src/components/contacts/SyncContactsFlow.web.tsx
@@ -0,0 +1,3 @@
+export function SyncContactsFlow() {
+  throw new Error('SyncContactsFlow is not available on web')
+}
diff --git a/src/components/contacts/phone-number.ts b/src/components/contacts/phone-number.ts
new file mode 100644
index 0000000000..df22aa2429
--- /dev/null
+++ b/src/components/contacts/phone-number.ts
@@ -0,0 +1,91 @@
+import {t} from '@lingui/macro'
+import {
+  ParseError,
+  parsePhoneNumber,
+  parsePhoneNumberWithError,
+  type PhoneNumber,
+} from 'libphonenumber-js/max'
+
+import {type CountryCode} from '#/lib/international-telephone-codes'
+
+/**
+ * Intended for after the user has finished inputting their phone number.
+ */
+export function processPhoneNumber(
+  number: string,
+  country: CountryCode,
+):
+  | {
+      valid: true
+      formatted: string
+    }
+  | {
+      valid: false
+      reason?: string
+    } {
+  try {
+    const phoneNumber = parsePhoneNumberWithError(number, {
+      defaultCountry: country,
+    })
+    if (!phoneNumber.isValid()) {
+      return {valid: false, reason: t`Invalid phone number`}
+    }
+    const type = phoneNumber.getType()
+    if (
+      type !== 'MOBILE' &&
+      type !== 'FIXED_LINE_OR_MOBILE' &&
+      type !== 'PERSONAL_NUMBER'
+    ) {
+      return {
+        valid: false,
+        reason: t`Number should be a mobile number`,
+      }
+    }
+    if (phoneNumber.country !== country) {
+      return {
+        valid: false,
+        reason: t`Country code does not match`,
+      }
+    }
+    return {
+      valid: true,
+      formatted: formatInternationalWithoutCountryCode(phoneNumber),
+    }
+  } catch (error) {
+    console.log(error)
+    if (error instanceof ParseError) {
+      return {valid: false, reason: error.message}
+    } else {
+      return {valid: false}
+    }
+  }
+}
+
+function formatInternationalWithoutCountryCode(phoneNumber: PhoneNumber) {
+  const intl = phoneNumber.formatInternational()
+  const prefix = '+' + phoneNumber.countryCallingCode
+  return intl.replace(prefix, '').trim()
+}
+
+export function getCountryCodeFromPastedNumber(
+  text: string,
+): {countryCode: CountryCode; rest: string} | undefined {
+  try {
+    const phoneNumber = parsePhoneNumber(text)
+    if (!phoneNumber.isValid()) {
+      return undefined
+    }
+    const countryCode = phoneNumber.country
+    // we don't have AC and TA in our dropdown - see `#/lib/international-telephone-codes`
+    if (countryCode && countryCode !== 'AC' && countryCode !== 'TA') {
+      return {
+        countryCode,
+        rest: formatInternationalWithoutCountryCode(phoneNumber),
+      }
+    } else {
+      return undefined
+    }
+  } catch (error) {
+    return undefined
+  }
+}
diff --git a/src/components/contacts/screens/PhoneInput.tsx b/src/components/contacts/screens/PhoneInput.tsx
index a265e40263..295858eaf8 100644
--- a/src/components/contacts/screens/PhoneInput.tsx
+++ b/src/components/contacts/screens/PhoneInput.tsx
@@ -6,7 +6,10 @@ import {msg, Trans} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
 import {useMutation} from '@tanstack/react-query'
 
-import {getDefaultCountry} from '#/lib/international-telephone-codes'
+import {
+  type CountryCode,
+  getDefaultCountry,
+} from '#/lib/international-telephone-codes'
 import {cleanError, isNetworkError} from '#/lib/strings/errors'
 import {logger} from '#/logger'
 import {useGeolocationStatus} from '#/state/geolocation'
@@ -18,6 +21,10 @@ import * as Layout from '#/components/Layout'
 import {InlineLinkText} from '#/components/Link'
 import {Loader} from '#/components/Loader'
 import {Text} from '#/components/Typography'
+import {
+  getCountryCodeFromPastedNumber,
+  processPhoneNumber,
+} from '../phone-number'
 import {type Action, type State} from '../state'
 
 export function PhoneInput({
@@ -40,24 +47,31 @@ export function PhoneInput({
   const [phoneNumber, setPhoneNumber] = useState(state.phoneNumber ?? '')
   const gutters = useGutters([0, 'wide'])
   const insets = useSafeAreaInsets()
+  // for API/generic errors
   const [error, setError] = useState('')
+  // for issues with parsing the number
+  const [formatError, setFormatError] = useState('')
 
   const {mutate: submit, isPending} = useMutation({
-    mutationFn: async ({}: {countryCode: string; phoneNumber: string}) => {
+    mutationFn: async ({}: {
+      phoneCountryCode: CountryCode
+      phoneNumber: string
+    }) => {
       // get otp
       await new Promise(resolve => {
         setTimeout(resolve, 500)
       })
     },
-    onSuccess: (_data, {countryCode, phoneNumber}) => {
+    onSuccess: (_data, {phoneCountryCode, phoneNumber}) => {
       dispatch({
         type: 'SUBMIT_PHONE_NUMBER',
-        payload: {phoneCountryCode: countryCode, phoneNumber},
+        payload: {phoneCountryCode, phoneNumber},
       })
     },
     onMutate: () => {
       Keyboard.dismiss()
       setError('')
+      setFormatError('')
     },
     onError: err => {
       if (isNetworkError(err)) {
@@ -73,6 +87,16 @@ export function PhoneInput({
     },
   })
 
+  const onSubmitNumber = () => {
+    const result = processPhoneNumber(phoneNumber, countryCode)
+    if (result.valid) {
+      setPhoneNumber(result.formatted)
+      submit({phoneCountryCode: countryCode, phoneNumber: result.formatted})
+    } else {
+      setFormatError(result.reason ?? _(msg`Invalid phone number`))
+    }
+  }
+
   const paddingBottom = Math.max(insets.bottom, tokens.space.xl)
 
   return (
@@ -126,32 +150,38 @@ export function PhoneInput({
               />
             </View>
             <View style={[a.flex_1]}>
-              <TextField.Root>
+              <TextField.Root isInvalid={!!formatError}>
                 <TextField.Input
                   label={_(msg`Phone number`)}
                   value={phoneNumber}
-                  onChangeText={setPhoneNumber}
+                  onChangeText={text => {
+                    if (formatError) setFormatError('')
+                    if (Math.abs(text.length - phoneNumber.length) > 1) {
+                      // possibly pasted/autocompleted? auto-switch
+                      // country code if possible
+                      const result = getCountryCodeFromPastedNumber(text)
+                      if (result) {
+                        setCountryCode(result.countryCode)
+                        setPhoneNumber(result.rest)
+                        return
+                      }
+                    }
+                    setPhoneNumber(text)
+                  }}
                   placeholder={null}
-                  keyboardType="phone-pad"
+                  keyboardType="number-pad" // we don't want people entering +() etc
                   autoComplete="tel"
                   returnKeyType={android('next')}
-                  onSubmitEditing={() => submit({countryCode, phoneNumber})}
+                  onSubmitEditing={onSubmitNumber}
                 />
               </TextField.Root>
             </View>
           </View>
         </View>
-        {error && (
-          <Text
-            style={[
-              a.text_md,
-              t.atoms.text_contrast_medium,
-              a.leading_snug,
-              a.mt_xl,
-            ]}>
-            {error}
-          </Text>
-        )}
+
+        {error && <ErrorText>{error}</ErrorText>}
+        {formatError && <ErrorText>{formatError}</ErrorText>}
+
         <View style={[a.mt_auto, a.py_xl]}>
           <LegalDisclaimer />
         </View>
@@ -165,7 +195,7 @@ export function PhoneInput({
             label={_(msg`Next`)}
             size="large"
             color="primary"
-            onPress={() => submit({countryCode, phoneNumber})}>
+            onPress={onSubmitNumber}>
             <ButtonText>
               <Trans>Next</Trans>
             </ButtonText>
@@ -217,3 +247,18 @@ function LegalDisclaimer() {
     </View>
   )
 }
+
+function ErrorText({children}: {children: string}) {
+  const t = useTheme()
+  return (
+    <Text
+      style={[
+        a.text_md,
+        {color: t.palette.negative_500},
+        a.leading_snug,
+        a.mt_md,
+      ]}>
+      {children}
+    </Text>
+  )
+}
diff --git a/src/components/contacts/state.ts b/src/components/contacts/state.ts
index 5a2909445f..b35483c2f1 100644
--- a/src/components/contacts/state.ts
+++ b/src/components/contacts/state.ts
@@ -1,6 +1,7 @@
 import {useReducer} from 'react'
 import {type ExistingContact} from 'expo-contacts'
 
+import {type CountryCode} from '#/lib/international-telephone-codes'
 import type * as bsky from '#/types/bsky'
 
 export type Contact = ExistingContact
@@ -14,12 +15,12 @@ export type Match = {
 export type State =
   | {
       step: '1: phone input'
-      phoneCountryCode?: string
+      phoneCountryCode?: CountryCode
       phoneNumber?: string
     }
   | {
       step: '2: verify number'
-      phoneCountryCode: string
+      phoneCountryCode: CountryCode
       phoneNumber: string
       lastSentAt: Date
     }
@@ -41,7 +42,7 @@ export type Action =
   | {
       type: 'SUBMIT_PHONE_NUMBER'
       payload: {
-        phoneCountryCode: string
+        phoneCountryCode: CountryCode
         phoneNumber: string
       }
     }
diff --git a/src/lib/international-telephone-codes.ts b/src/lib/international-telephone-codes.ts
index 355769b47b..b2a7d3d4c0 100644
--- a/src/lib/international-telephone-codes.ts
+++ b/src/lib/international-telephone-codes.ts
@@ -1,3 +1,14 @@
+import {type CountryCode as LibPhoneNumberJsCountryCode} from 'libphonenumber-js'
+
+// Exclude Ascension Island and Tristan da Cunha - merged into `SH` in 2009
+export type CountryCode = Exclude<LibPhoneNumberJsCountryCode, 'AC' | 'TA'>
+
+/**
+ * Note: data is from Wikipedia, but some have been removed to match `libphonenumber-js`
+ * Mostly tiny British overseas territories + Antarctica, all of which
+ * share codes with a larger country. If you've one of the 10 people from these
+ * places, you probably know what to do.
+ */
 export const INTERNATIONAL_TELEPHONE_CODES = {
   AD: {
     code: '+376',
@@ -34,11 +45,13 @@ export const INTERNATIONAL_TELEPHONE_CODES = {
     unicodeFlag: '🇦🇴',
     svgFlag: require('../../assets/icons/flags/AO.svg'),
   },
-  AQ: {
-    code: '+672',
-    unicodeFlag: '🇦🇶',
-    svgFlag: require('../../assets/icons/flags/AQ.svg'),
-  },
+  // sorry penguins :(
+  // same as Norfolk Island
+  // AQ: {
+  //   code: '+672',
+  //   unicodeFlag: '🇦🇶',
+  //   svgFlag: require('../../assets/icons/flags/AQ.svg'),
+  // },
   AR: {
     code: '+54',
     unicodeFlag: '🇦🇷',
@@ -154,11 +167,12 @@ export const INTERNATIONAL_TELEPHONE_CODES = {
     unicodeFlag: '🇧🇹',
     svgFlag: require('../../assets/icons/flags/BT.svg'),
   },
-  BV: {
-    code: '+47',
-    unicodeFlag: '🇧🇻',
-    svgFlag: require('../../assets/icons/flags/BV.svg'),
-  },
+  // same as Norway
+  // BV: {
+  //   code: '+47',
+  //   unicodeFlag: '🇧🇻',
+  //   svgFlag: require('../../assets/icons/flags/BV.svg'),
+  // },
   BW: {
     code: '+267',
     unicodeFlag: '🇧🇼',
@@ -379,11 +393,12 @@ export const INTERNATIONAL_TELEPHONE_CODES = {
     unicodeFlag: '🇬🇷',
     svgFlag: require('../../assets/icons/flags/GR.svg'),
   },
-  GS: {
-    code: '+500',
-    unicodeFlag: '🇬🇸',
-    svgFlag: require('../../assets/icons/flags/GS.svg'),
-  },
+  // same as Falkland Islands
+  // GS: {
+  //   code: '+500',
+  //   unicodeFlag: '🇬🇸',
+  //   svgFlag: require('../../assets/icons/flags/GS.svg'),
+  // },
   GT: {
     code: '+502',
     unicodeFlag: '🇬🇹',
@@ -779,11 +794,12 @@ export const INTERNATIONAL_TELEPHONE_CODES = {
     unicodeFlag: '🇵🇲',
     svgFlag: require('../../assets/icons/flags/PM.svg'),
   },
-  PN: {
-    code: '+64',
-    unicodeFlag: '🇵🇳',
-    svgFlag: require('../../assets/icons/flags/PN.svg'),
-  },
+  // same as New Zealand
+  // PN: {
+  //   code: '+64',
+  //   unicodeFlag: '🇵🇳',
+  //   svgFlag: require('../../assets/icons/flags/PN.svg'),
+  // },
   PR: {
     code: '+1',
     unicodeFlag: '🇵🇷',
@@ -1199,11 +1215,12 @@ export const INTERNATIONAL_TELEPHONE_CODES = {
     unicodeFlag: '🇫🇴',
     svgFlag: require('../../assets/icons/flags/FO.svg'),
   },
-  HM: {
-    code: '+672',
-    unicodeFlag: '🇭🇲',
-    svgFlag: require('../../assets/icons/flags/HM.svg'),
-  },
+  // same as Norfolk Island
+  // HM: {
+  //   code: '+672',
+  //   unicodeFlag: '🇭🇲',
+  //   svgFlag: require('../../assets/icons/flags/HM.svg'),
+  // },
   KM: {
     code: '+269',
     unicodeFlag: '🇰🇲',
@@ -1229,16 +1246,18 @@ export const INTERNATIONAL_TELEPHONE_CODES = {
     unicodeFlag: '🇹🇨',
     svgFlag: require('../../assets/icons/flags/TC.svg'),
   },
-  TF: {
-    code: '+672',
-    unicodeFlag: '🇹🇫',
-    svgFlag: require('../../assets/icons/flags/TF.svg'),
-  },
-  UM: {
-    code: '+1',
-    unicodeFlag: '🇺🇲',
-    svgFlag: require('../../assets/icons/flags/UM.svg'),
-  },
+  // same as Norfolk Island
+  // TF: {
+  //   code: '+672',
+  //   unicodeFlag: '🇹🇫',
+  //   svgFlag: require('../../assets/icons/flags/TF.svg'),
+  // },
+  // same as US mainland
+  // UM: {
+  //   code: '+1',
+  //   unicodeFlag: '🇺🇲',
+  //   svgFlag: require('../../assets/icons/flags/UM.svg'),
+  // },
   VA: {
     code: '+39',
     unicodeFlag: '🇻🇦',
@@ -1249,25 +1268,33 @@ export const INTERNATIONAL_TELEPHONE_CODES = {
     unicodeFlag: '🇽🇰',
     svgFlag: require('../../assets/icons/flags/XK.svg'),
   },
-}
+} satisfies Record<
+  CountryCode,
+  {
+    code: string
+    unicodeFlag: string
+    svgFlag: any
+  }
+>
 
-const DEFAULT_PHONE_COUNTRY = 'US'
+const DEFAULT_PHONE_COUNTRY = 'US' as const
 
-export function getDefaultCountry(location?: {countryCode?: string}) {
+export function getDefaultCountry(location?: {
+  countryCode?: string
+}): CountryCode {
+  const locationCountryCode = location?.countryCode?.toUpperCase()
   if (
-    location?.countryCode &&
-    location.countryCode.toUpperCase() in INTERNATIONAL_TELEPHONE_CODES
+    locationCountryCode &&
+    locationCountryCode in INTERNATIONAL_TELEPHONE_CODES
   ) {
-    return location.countryCode.toUpperCase()
+    return locationCountryCode as CountryCode
   }
   return DEFAULT_PHONE_COUNTRY
 }
 
 export function getPhoneCodeFromCountryCode(countryCode: string) {
   const country =
-    INTERNATIONAL_TELEPHONE_CODES[
-      countryCode.toUpperCase() as keyof typeof INTERNATIONAL_TELEPHONE_CODES
-    ]
+    INTERNATIONAL_TELEPHONE_CODES[countryCode.toUpperCase() as CountryCode]
   if (!country) throw new Error(`Country ${countryCode} not found`)
   return country.code
 }
diff --git a/yarn.lock b/yarn.lock
index 3b320fcae0..4ddb35f011 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -14235,6 +14235,11 @@ levn@^0.4.1:
     prelude-ls "^1.2.1"
     type-check "~0.4.0"
 
+libphonenumber-js@^1.12.30:
+  version "1.12.30"
+  resolved "https://registry.yarnpkg.com/libphonenumber-js/-/libphonenumber-js-1.12.30.tgz#8f37c6d0546e89a399085d329214a583642e611a"
+  integrity sha512-KxH7uIJFD6+cR6nhdh+wY6prFiH26A3W/W1gTMXnng2PXSwVfi5MhYkdq3Z2Y7vhBVa1/5VJgpNtI76UM2njGA==
+
 lighthouse-logger@^1.0.0:
   version "1.4.2"
   resolved "https://registry.yarnpkg.com/lighthouse-logger/-/lighthouse-logger-1.4.2.tgz#aef90f9e97cd81db367c7634292ee22079280aaa"