Paste the IP that sites actually see, through the proxy, not the box you connect to.
Shows ASN, org, country, and whether it looks mobile, broadband, or datacentre. Runs in your browser. No signup.
Tip: get the exit with curl -x http://USER:PASS@HOST:PORT https://api.ipify.org.
Dedicated UK 4G exits usually look like O2 / giffgaff mobile, not a cloud ASN.