Customer Reviews
Questions?  Call us today!  800-929-8061

TN556D ISDN BRI 4-Wire S/T-NT Interface

Please call for availability.
This product is eligible for 2 Year Platinum Protection!

TN556D Features

  • Provides 12-Ports connecting to ISDN-BRI terminals
  • Each port has TXT, TXR, PXT, and PXR signal leads
  • Up to 8 ports can be used for adjunct switch application interface (ASAI) links
  • Each port operates at 192 kbps per second and has 2 B-channels and 1 D-channel
  • Requires a packet control circuit pack (TN778) when used in R6si systems or packet bus-equipped R6vs systems
  • Range of up to 3300 ft. maximum from the system to the voice terminal
  • Can connect 24 terminals where each terminal uses 1 B-channel and shares the D-channel
  • Compatible with Definity R7 or later

best live chat
  • Find us on Facebook
  • Find an installer at