t1 slotslotport: Slot number and port number where the channelized E1 or T1 controller is located. number : Channelized E1 or T1 controller number. timeslots: For ISDN, the D channel timeslot,What Is New For T1 Version 2.5. SHOW VIDEO & PHOTOS. Better Surface Finish. The Front, Top, and Bottom Panels have been upgraded to a finer