Network termination 1

Network Termination 1 (NT1): In Integrated Services Digital Networks (ISDN), a functional grouping of customer-premises equipment that includes functions that may be regarded as belonging to OSI Layer 1, i.e., functions associated with ISDN electrical and physical terminations on the user premises.

Note: The NT1 forms a boundary to the network and may be controlled by the provider of the ISDN services.

The physical equipment is also known as a terminal adapter. In the United states the customer usually has to provide the NT1, whereas in other countries it is usually the carrier company that provides it.

The interface from the NT1 to the telephone exchange is the U interface. Customer equipment commons connects via an S bus but may also use USB, or a serial port.

References

 This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C".