grep with regex for phone number

Question

I would like to get the phone numbers from a file. I know the numbers have different forms, I can handle for a single one, but don\'t know how to get a uniform regex. For ex

Answer 1

We can put all the required phone number validations one by one using an or condition which is more likely to work well (but tiresome coding).

grep '^[0-9]\{10\}$\|^[0-9]\{3\}[-][0-9]\{3\}[-][0-9]\{4\}$\|^[0-9]\{3\}[ ][0-9]\{3\}[ ][0-9]\{4\}$\|^[(][0-9]\{3\}[)][0-9]\{3\}[-][0-9]\{4\}$' phone_number.txt

returns all the specific formats :

• 920-702-9999
• (920)702-9999
• 920 702 9999
• 9207029999