<!DOCTYPE html>
<html>
<body>
<h1>Display a Telephone Input Field</h1>
<form action="https://www.cs.umn.edu/">
<label for="phone">Enter a phone number:</label><br><br>
<input type="text" pattern="^[2-9]\d{2}-\d{3}-\d{4}$"/>
<small>Format: 123-456-6789</small><br><br>
<input type="submit">
</form>
</body>
</html>