Additional Details ------------------------------ Product description: TN464GP Universal DS1/ISDN Circuit Pack Like New: This product is eligible for 2 Year Platinum Protection! TN464GP Features Supports DS1 Rate (24 Digital Channels) and E1 Rate (32 Digital Channels) All versions support CO, TIE, DID and OPS (Off - Premises Stations) port types using the robbed signal protocol, proprietary bit-oriented signaling, (BOS) 24th channel signaling protocol, and the DMI-BOS 24th channel signaling protocol All versions also support ISDN-PRI connectivity TN464E and later provide test jack access to the DS1 or E1 line and support the 120A Integrated CSU TN464F and later suffix is required to communicate with Conversant TN464GP provides echo cancellation and downloadable firmware capabilities for Definity Release 9 and later TN464GP backwards compatible with earlier Definity Releases Firmware download feature requires use of the TN799C C-LAN interface