Avaya TN747B Definity PBX Expansion Card

The Avaya TN747B is a Central Office (CO) Trunk circuit pack designed to provide analogue trunk connectivity between a PBX system and the public switched telephone network (PSTN). This card enables the connection of traditional analogue telephone lines to the switching system, handling incoming and outgoing calls via CO trunk circuits.

The TN747B is engineered for use within Avaya Definity and G3 series communication servers. It slots into the system’s universal card cage and provides multiple trunk ports for analogue line termination, supporting standard loop-start or ground-start signalling depending on configuration.

This is a legacy circuit pack from Avaya’s established Definity platform, which has been superseded by newer IP-based communication solutions. However, many organisations continue to operate Definity systems and require replacement or spare TN747B cards to maintain their existing infrastructure.

Available from Tech Star as new or refurbished stock. Submit a price enquiry for availability and lead time.