Day 15 : ISDN Reference Points

Equipment

TE1 - Terminal Equipment type 1 (devices has built-in IDSN connection)
TE2 - Terminal Equipment type 2 (devices that do not understand ISDN standard)
TA - Terminal Adapter (connectes TE2 to ISDN network)

Reference Points

R - ref point between non-ISDN device (TE2) and TA
S - ref point between ISDN device and NT2
T - ref point between NT2 and NT1
U - ref point between NT1 and ISDN network

* In North America and Japan, ISDN devices has U interface. Customer equipment (CPE) has NT1.
** In Europe, ISDN devices has S/T interface. Service provider provide NT1 service in central office equipment.