Nortel M3900 Series Snap-in Accessories expand the features and services of the display-based M3900 Digital Telephones. These easily installed snap-in cartridges are:  Analog Terminal Adapter, External Alerter and Recording Interface, Personal Directory PC Utility, Computer Telephony Integration Adapter, and Full Duplex Handsfree Module.

• Meridian Analog Terminal Adapter (ATA) provides an analog connection directly through a M3900 series phone for an economical analog connection to devices such as Fax machines, Laptop or PC modems.
• Meridian External Alerter and Recording Interface provides call-in-progress or ringing indication through a connection to an external alerting device, such as a loud bell or flashing light.
• Personal Directory PC Utility provides a fast and convenient way to transfer the directory contents from one telephone to another or create the contents of the Personal Directory by entering it into a PC then downloading to the telephone.
• Computer Telephony Integration Adapter (CTIA) and accompanying TAPI software allows a user to dial from TAPI compliant software applications such as Outlook and ACT.
• Full Duplex Handsfree Module for the M3904 provides the ability to conduct two-way simultaneous conversations in Handsfree mode.