How do I retrieve the visitor's ISP through PHP?

Question

How do I find out the ISP provider of a person viewing a PHP page?

Is it possible to use PHP to track or reveal it?

If I use something like the following:

Answer 1

Why not use ARIN's REST API.

Handle: {$result->net->handle->{'$'}}
Ref: {$result->net->ref->{'$'}}
Name: {$result->net->name->{'$'}}
echo "OrgRef: {$result->net->orgRef->{'@name'}}";

END; // eof

https://www.arin.net/resources/whoisrws/whois_api.html