I think that using the phone number to identify providers is only partially useful.  I type in lots of phone numbers (10 digits, all together and alternatively 3 digit area code plus 7 digit number on 2nd line) and get no reviews found.  Even when I type in a phone number that I know is there because I wrote the review myself.  What is the proper way to enter a phone number to get reliable info?

I've tried
123456789(10)
and
(123) 45678910

Neither way finds the review that I wrote and I assume therefore that it fails on a number of other reviews.

...Don't use parentheses for the area code and don't use a hyphen for the phone no.

Here's what TER says:

"2.  When searching on 'provider's phone number:', enter just the last seven digits, and leave both the area code and city fields blank.  If any profiles exist in the database with the phone number, this approach will find it -- regardless of any data entry errors in the city or area code fields submitted by previous reviewers."

As I recall, even just a few digits will work.  That is, entering "1234" will return all phone numbers with the sequence 1234 anywhere in the complete number.  

212-346-9876 has a "1234"
203-321-2349 has a "1234"
etc