Filtering out Phone numbers

[d-woo]

Newbie here...

I am using a PHP message board where guest sometimes enter their phone numbers in the comments portion.

How would I filter and convert phone numbers to asterisks?

The first 3 characters and the last four would be the only ones I would really need to change.

EG. 310-123-4567 to -123-*

Also some people enter phone numbers with parentheses and others without, some with dashes, some without.

Any help would be greatly appreciated.

Thanks.

[Anon]

Have you considered using regular expressions?

You might need to filter several different ways but once you'd worked out how to do the reg.exp. it would be quick. You could just look for clusters of 3 numbers rather than phone numbers. If they are comments being added then numbers aren't probably being added for other reasons.