diff --git a/README.md b/README.md
index 60deabb..283318a 100644
--- a/README.md
+++ b/README.md
@@ -36,7 +36,8 @@ const Demo = () => {
 }
 ```
 
-For including the styles, you should import them in the main `less` file after importing either the `antd/dist/antd.less` or `antd/dist/antd.dark.less` styles.
+For including the styles, you should import them in the main `less` file after importing either
+the `antd/dist/antd.less` or `antd/dist/antd.dark.less` styles.
 
 ```diff
 @import "~antd/dist/antd";
@@ -63,10 +64,31 @@ number into a single string.
   "countryCode": 1,
   "areaCode": 702,
   "phoneNumber": "1234567",
-  "isoCode": "us"
+  "isoCode": "us",
+  "valid": true
 }
 ```
 
+## Validation
+
+The `valid` property of the value object shows the real-time validity of the phone number depending on the country. So
+this can be used in a `validator` like this:
+
+```javascript
+const validator = (_, {valid}) => {
+  if (valid) {
+    return Promise.resolve();
+  }
+  return Promise.reject("Invalid phone number");
+}
+
+return (
+  <FormItem rules={[{validator}]}>
+    <PhoneInput/>
+  </FormItem>
+)
+```
+
 ## Props
 
 | Property           | Description                                                                                                                     | Type                |
diff --git a/package.json b/package.json
index 4a344de..4926b66 100644
--- a/package.json
+++ b/package.json
@@ -1,5 +1,5 @@
 {
-  "version": "0.1.1",
+  "version": "0.1.2",
   "name": "antd-phone-input",
   "description": "Advanced Phone Number Input for Ant Design",
   "keywords": [
diff --git a/src/index.tsx b/src/index.tsx
index 6edddbb..c6d9e3a 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -5,6 +5,7 @@ import {ParsePhoneNumber, PhoneInputProps, ReactPhoneOnChange, ReactPhoneOnMount
 
 import masks from "./phoneMasks.json";
 import timezones from "./timezones.json";
+import validations from "./validations.json";
 
 import "react-phone-input-2/lib/style.css";
 
@@ -35,7 +36,14 @@ const parsePhoneNumber: ParsePhoneNumber = (value, data, formattedNumber) => {
 	const phoneNumberMatch = value ? (value.match(phoneNumberPattern) || []) : [];
 	const phoneNumber = phoneNumberMatch.length > 1 ? phoneNumberMatch[1] : null;
 
-	return {countryCode, areaCode, phoneNumber, isoCode};
+	/** Checks if both the area code and phone number length satisfy the validation rules */
+	const rules = validations[isoCode as ISO2Code] || {areaCode: [], phoneNumber: []};
+	const valid = [
+		rules.areaCode.includes((areaCode || "").toString().length),
+		rules.phoneNumber.includes((phoneNumber || "").toString().length),
+	].every(Boolean);
+
+	return {countryCode, areaCode, phoneNumber, isoCode, valid};
 }
 
 const PhoneInput = ({
@@ -79,8 +87,8 @@ const PhoneInput = ({
 
 	const onMount: ReactPhoneOnMount = (rawValue, {countryCode, ...event}, formattedNumber) => {
 		const metadata = parsePhoneNumber(rawValue, {countryCode}, formattedNumber);
-		/** Initiates the existing value when Antd FormItem is used */
-		if (value === undefined) handleChange(metadata, event);
+		/** Initializes the existing value */
+		handleChange(metadata, event);
 		handleMount(metadata);
 	}
 
diff --git a/src/types.ts b/src/types.ts
index 26d5ab1..fd72315 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -9,6 +9,7 @@ export interface PhoneNumber {
 	areaCode?: number | null,
 	phoneNumber?: string | null,
 	isoCode?: string,
+	valid?: boolean,
 }
 
 export interface AntInputProps {
@@ -17,9 +18,7 @@ export interface AntInputProps {
 	style?: CSSProperties,
 	className?: string,
 	disabled?: boolean,
-}
 
-export interface AntInputEventsProps {
 	onChange?(value: PhoneNumber, event: ChangeEvent<HTMLInputElement>): void;
 
 	onPressEnter?(event: KeyboardEvent<HTMLInputElement>): void;
@@ -37,9 +36,7 @@ export interface ReactPhoneInputProps {
 	onlyCountries?: string[],
 	excludeCountries?: string[],
 	preferredCountries?: string[],
-}
 
-export interface ReactPhoneEventsProps {
 	onFocus?(event: FocusEvent<HTMLInputElement>, value: PhoneNumber): void;
 
 	onClick?(event: MouseEvent<HTMLInputElement>, value: PhoneNumber): void;
@@ -63,7 +60,9 @@ export interface ParsePhoneNumber {
 	(value: string, data: CountryData, formattedNumber: string): PhoneNumber;
 }
 
-export interface PhoneInputProps extends AntInputProps, AntInputEventsProps, ReactPhoneInputProps, ReactPhoneEventsProps {
-	// TODO add onValidate: https://github.com/ArtyomVancyan/antd-phone-input/issues/19
-	// onValidate?: (value: PhoneNumber) => boolean;
+export interface PhoneInputProps extends AntInputProps, ReactPhoneInputProps {
+	/**
+	 * NOTE: Interfaces of events may differ from the original interfaces
+	 * of dependencies, so be careful and follow the linked documentation.
+	 */
 }
diff --git a/tests/common.test.tsx b/tests/common.test.tsx
index f4cdd08..6d5354b 100644
--- a/tests/common.test.tsx
+++ b/tests/common.test.tsx
@@ -33,9 +33,11 @@ describe("Checks the basic rendering and functionality", () => {
 				assert(value.areaCode === 702);
 				assert(value.phoneNumber === "1234567");
 				assert(value.isoCode === "us");
+				assert(value.valid === true);
 			}}
 			value={{countryCode: 1, areaCode: 702, phoneNumber: "1234567"}}
 		/>);
+		assert(screen.getByDisplayValue("+1 (702) 123 4567"));
 	})
 
 	it("Checks the component on user input", async () => {
@@ -67,4 +69,19 @@ describe("Checks the basic rendering and functionality", () => {
 		assert(input.getAttribute("value") === "+1 (702) 123 4567");
 		screen.getByTestId("button").click();
 	})
+
+	it("Checks input validation with FormItem", async () => {
+		render(<Form initialValues={{phone: {countryCode: 1, areaCode: 702, phoneNumber: "1234567"}}}>
+			<FormItem name="phone" rules={[{
+				validator: (_, {valid}) => {
+					assert(valid === true);
+					return Promise.resolve();
+				}
+			}]}>
+				<PhoneInput/>
+			</FormItem>
+			<Button data-testid="button" htmlType="submit">Submit</Button>
+		</Form>);
+		await userEvent.click(screen.getByTestId("button"));
+	})
 })