Tool to check payment hosting providers for ecommerce applications

hi all,
I'm throwing out a question that someone may be aware of.
Is there any way/tools/software of checking an individual website's payment hosting provider?
For example, a merchant is using an unknown hosting provider when they should be using something like Sagepay/Protex/Worldpay.. is there any way of detecting what payment hosting provider they are actually using by going through their website/IP address?


Thanks & Regards,
Laura