A user with a Digital Communications Protocol (DCP), hybrid, IP, wireless, or ISDN-BRI telephones can use the Conference feature for a call on hold when:
If more than one call is on hold, the user must make a call active to start a conference. If the user presses the conf button when two or more calls are on hold, the system ignores the conference request from the user.
If the user has an active call, and also has calls on hold, the system includes the active call in the conference when the user presses the conf button.
