Is there a way to search on here for info about a provider using the telephone number?
Yes, but I think it is experiencing issues right now! The way to do it is to click on the "SEARCH" link in the Banner near the top of the page (near right side). From there you should see a Keyword block that you can type whatever you are searching for, i.e. phone number and then click the Search Now button at the bottom. If you want to narrow the area that you are looking in, use the Search in Forum list to pick where you are looking for that phone number, such as Mississippi Independent Reviews, etc.
I know the Search function was being worked on a while back, but never heard whether it was fixed. When it did work, the results weren't always accurate when searching by phone number, which I think was due to the dash marks. That caused it to also match partial phone numbers, like all the 228 prefixes!
The easiest way is to use Google with the "site" feature. For example, in Google type
123-456-7890 site:eccie.net
The "site:eccie.net" causes Google to limit the search to the site you specify.