diff --git a/apps/web/components/phone-input/PhoneInput.test.ts b/apps/web/components/phone-input/PhoneInput.test.ts
new file mode 100644
index 0000000000..51c074da81
--- /dev/null
+++ b/apps/web/components/phone-input/PhoneInput.test.ts
@@ -0,0 +1,53 @@
+import { isValidPhoneNumber, parsePhoneNumberFromString } from "libphonenumber-js/max";
+import { describe, expect, it } from "vitest";
+import { CUSTOM_PHONE_MASKS } from "./phone-masks";
+
+/** Count the digit placeholders (dots) in a react-phone-input-2 mask */
+const countMaskDigits = (mask: string): number => (mask.match(/\./g) || []).length;
+
+/**
+ * Test phone numbers that must be accepted for each country with a custom mask.
+ * These are realistic mobile and landline numbers validated by libphonenumber-js.
+ */
+const COUNTRY_TEST_NUMBERS: Record<string, { number: string; description: string }[]> = {
+  ci: [{ number: "+2250797764877", description: "Ivory Coast 10-digit mobile" }],
+  bj: [{ number: "+2290165526657", description: "Benin 10-digit mobile" }],
+  at: [{ number: "+436641234567", description: "Austria mobile" }],
+  ar: [
+    { number: "+5491112345678", description: "Argentina mobile (Buenos Aires, 11 national digits)" },
+    { number: "+5493414123456", description: "Argentina mobile (Rosario, 11 national digits)" },
+    { number: "+541112345678", description: "Argentina landline (10 national digits)" },
+  ],
+  fi: [
+    { number: "+3584012345678", description: "Finland 10-digit mobile" },
+    { number: "+358501234567", description: "Finland 9-digit mobile" },
+  ],
+};
+
+describe("CUSTOM_PHONE_MASKS", () => {
+  describe.each(Object.entries(CUSTOM_PHONE_MASKS))("mask for %s", (countryCode, mask) => {
+    const maskDigits = countMaskDigits(mask);
+    const testNumbers = COUNTRY_TEST_NUMBERS[countryCode] || [];
+
+    it("should have enough digit placeholders for all valid phone numbers", () => {
+      for (const { number, description } of testNumbers) {
+        const parsed = parsePhoneNumberFromString(number);
+        expect(parsed, `Failed to parse ${description}: ${number}`).toBeTruthy();
+
+        const nationalDigits = parsed?.nationalNumber.length ?? 0;
+        expect(
+          maskDigits,
+          `Mask for ${countryCode} has ${maskDigits} digit slots but ${description} (${number}) needs ${nationalDigits} national digits`
+        ).toBeGreaterThanOrEqual(nationalDigits);
+      }
+    });
+
+    it("should have test numbers that pass libphonenumber-js validation", () => {
+      for (const { number, description } of testNumbers) {
+        expect(isValidPhoneNumber(number), `${description} (${number}) should be a valid phone number`).toBe(
+          true
+        );
+      }
+    });
+  });
+});
diff --git a/apps/web/components/phone-input/PhoneInput.tsx b/apps/web/components/phone-input/PhoneInput.tsx
index 8894a9cc3d..a82ab7b1d6 100644
--- a/apps/web/components/phone-input/PhoneInput.tsx
+++ b/apps/web/components/phone-input/PhoneInput.tsx
@@ -2,20 +2,15 @@
 
 import { isSupportedCountry } from "libphonenumber-js";
 import type { CSSProperties } from "react";
-import { useState, useEffect } from "react";
+import { useEffect, useState } from "react";
 import PhoneInput from "react-phone-input-2";
 import "react-phone-input-2/lib/style.css";
 
 import { useIsPlatform } from "@calcom/atoms/hooks/useIsPlatform";
-import { useBookerStore, type CountryCode } from "@calcom/features/bookings/Booker/store";
+import { type CountryCode, useBookerStore } from "@calcom/features/bookings/Booker/store";
 import { trpc } from "@calcom/trpc/react";
 import classNames from "@calcom/ui/classNames";
-
-const CUSTOM_PHONE_MASKS = {
-  ci: ".. .. .. .. ..",
-  bj: ".. .. .. .. ..",
-  at: "... ..........",
-};
+import { CUSTOM_PHONE_MASKS } from "./phone-masks";
 
 export type PhoneInputProps = {
   value?: string;
diff --git a/apps/web/components/phone-input/phone-masks.ts b/apps/web/components/phone-input/phone-masks.ts
new file mode 100644
index 0000000000..1dcd02818e
--- /dev/null
+++ b/apps/web/components/phone-input/phone-masks.ts
@@ -0,0 +1,20 @@
+/**
+ * Custom phone masks to override outdated masks in react-phone-input-2.
+ * The library's built-in masks can lag behind countries' numbering plan changes,
+ * causing valid phone numbers to be truncated (users can't type enough digits).
+ *
+ * Each dot (.) represents a digit placeholder. When a country updates its
+ * numbering plan to use longer numbers, add an override here.
+ */
+export const CUSTOM_PHONE_MASKS = {
+  /** Ivory Coast: migrated from 8 to 10 digits in 2021 */
+  ci: ".. .. .. .. ..",
+  /** Benin: migrated from 8 to 10 digits in 2025 */
+  bj: ".. .. .. .. ..",
+  /** Austria: variable-length numbers up to 13 digits */
+  at: "... ..........",
+  /** Argentina: mobile numbers require 11 national digits (9 + area code + subscriber) */
+  ar: "(..) .........",
+  /** Finland: some mobile numbers use 10 national digits */
+  fi: ".. ... .. ...",
+};