phone number tag in html code example

Example 1: html telephone link

One click should open the phone dialler and input the number to be called.
<a href="tel:5551234567">Call (555)123-4567</a>

Example 2: html make phone number callable

Area code with dashes, 1 and + sign

<a href="tel:+1-555-555-1212">555-555-1212</a>
Area code with no dashes, 1 and + sign

<a href="tel:+15555551212">555-555-1212</a>

Example 3: phone number validation html

How about this? /(7|8|9)\d{9}/

It starts by either looking for 7 or 8 or 9, and then followed by 9 digits.