Arcareach | Sigma is an inverse NT-1 that changes an S interface (NT side) into a U interface (LT side) and provides power feeding (70V) on the U interface.
Many digital PBXs offer ISDN S-bus interfaces as standard which can operate up to 0.9km (3000ft) under certain conditions. When there is a requirement for the S-bus to be located much further from the PBX the Arcareach | Sigma can be used to turn the S-bus interface into a U interface, supporting 2B1Q encoding.
Using Arcareach | Sigma an S interface can be extended up to 5km by installing an NT-1 at the far end.
