Here is one company that allows you to use a dynamic IP address with a service that requires a fixed IP address. Anyone with a T1 or similar Internet connection probably already has a fixed IP address. Fixed just means that it does not change. Cable modems and DSL lines often don't have fixed IP addresses. This can be a form of security because hackers will not know where to find your computer because the address is constantly changing.
The problem with a constantly changing address is that services that need to find you, such as a VPN, will not be able to find you. Small schools or auxiliary buildings may have dynamic addresses and a need to be found. Services, such as the one linked to below, can monitor your dynamic address and update your domain name. So, abc.edu could be 220.127.116.11 on Monday and 18.104.22.168 on Tuesday. Your device would always be able to find the right place because the domain name is fixed.
No-IP - Dynamic DNS, Static DNS for Your Dynamic IP: "No-IP is a dynamic dns provider, both free and paid, backed by our industry proven network of highly available nameservers."