Final answer:
The term for access by users or information systems communicating external to an information system security perimeter is Extranet access.
Step-by-step explanation:
Extranet access
The term for access by users or information systems communicating external to an information system security perimeter is Extranet access. An extranet is a private network that allows authorized external parties, such as customers, suppliers, partners, or remote employees, to access a company's internal resources. It extends the organization's network to provide controlled access to external users while maintaining security.