Old static IP's

IP address will be provided by the ISP either fixed or dynamic
and that IP address will be in the database for that ISP
so in theory no difference between them giving a fixed IP or a dynamic IP

and depending on the ISP - you may have a dynamic IP address and it not change - as modems are often always connected and if disconnected may not change the IP address for a certain time limit anyway

or have i misunderstood the question