You need IP whitelists to use EPP, the domain name list, the sandbox, and the registrar portal. On the registrar portal, you can even whitelist your IP address for the other services.
If you need to log in to the registrar portal, make sure that you are registered as a user and that the IP address you log in from is whitelisted in the registrar portal.
If the above is not the case, you will not be able to access the registrar portal. You must therefore contact a user in your organization who already has access and is the administrator of your REG handle, who can then whitelist the desired IP address and / or create you as a user.