With PSA, different users can use the same group of telephones at different times. For example, several telecommuting users can use the same office on different days of the week. The users use PSA to associate with the office telephone. When a user associates the telephone, the telephone is assigned to that user. For example, the user can originate and receive calls.

At home, a telecommuting user can also use PSA to install a digital communications protocol (DCP) telephone and a DEFINITY Extender. The user can then call into the system, and use PSA to associate the home telephone with the extension that is assigned to the user at the office. When someone calls the user extension, the call rings at the home of the user.

When a user no longer wants to use PSA, the user disassociates from the telephone.

PSA requires a user to enter a security code, from either an onsite or an off-site telephone.