accurate ASN lookup is tripping me up for ISP identification

we're running a web tool like 'What is My ISP?' and are constantly refining its accuracy. it's a critical component for our user base.

the thing is, we're hitting a wall with the precision of our ASN lookup methods, specifically when it comes to consistently correlating IPs to the correct ISP. this is especially tricky for smaller or regional providers where public ASN database info might be sparse or outdate.

we're seeking advanced, perhaps non-standard, techniques beyond typical reverse DNS or basic public databases to improve our ISP identification success rate. any insights into more robust network intelligence or BGP data analysis would be awesome. help a brother out please...