Nortel Networks 6.1 Direct inward system access Disa, Class of Service COS, Maintaining security

238 / Using System features

Direct inward system access (DISA)

Control access to your Norstar system with direct inward system access (DISA). Access to your Norstar system from the public telephone network should always be controlled with DISA. If your installer or customer service representative programs the line used for remote access to answer a call automatically and wait for a DISA internal number, callers hear a stuttered dial tone and must enter a Class of Service password before they are allowed into the system.

Class of Service (COS)

To control the level of telephone service a remote user can access, your installer can assign a remote filter and remote package to the line used for remote access. The remote filter restricts the numbers that can be dialed on the line, and the remote package restricts the use of line pools and the page feature. To change the restrictions for the line, the user can enter their Class of Service (COS) password when the system answers with DISA, or can dial the DISA internal number and enter their Class of Service password.

Maintaining security

To maintain the security of your system, the following practices are recommended:

•Warn anyone to whom you give the remote access number to keep it confidential.

•Change Class of Service passwords often.

•Warn anyone to whom you give a Class of Service password to remember it and not to write it down.

•Remove the Class of Service password of anyone who leaves your company.

Compact ICS 6.1 System Coordinator Guide P0603544 02