ISDN NT/TE

ISDN is a system with digitized phone connections which has been pure analogue connection for a decade. This is the first protocol defines on a digital communications line that allows for the transmission of voice, data, video and graphics, at very high speeds, over standard communication lines simultaneously, carried by bearer channels (B channels) occupying a bandwidth of 64 kbits per second (some switches limit it to a capacity of 56 kb/s). A data channel (D channel) is defined handles signaling at 16 kb/s or 64 kb/s, depending on the service type. ISDN is not restricted to public telephone networks alone; it may be transmitted via packet switched networks, telex, CATV networks, etc. There are two basic types of ISDN service:

• Basic Rate Interface(BRI) - consists of two 64 kb/s B channels and one 16 kb/s D channel for a total of 144 kb/s. This basic service is intended to meet the needs of most individual users. The U interface provided by the telco for BRI is a 2-wire, 160 kb/s digital connection. Echo cancellation is used to reduce noise, and data encoding schemes (2B1Q in North America, 4B3T in Europe) permit this relatively high data rate over ordinary single-pair local loops.
• Primary Rate Interface (PRI) which is intended for users with greater capacity requirements. Typically the channel structure is 23 B channels plus one 64 kb/s D channel for a total of 1536 kb/s. In Europe, PRI consists of 30 B channels plus one 64 kb/s D channel for a total of 1984 kb/s. It is also possible to support multiple PRI lines with one 64 kb/s D channel using Non-Facility Associated Signaling (NFAS).

EuroISDN is actually the name given to the Memorandum of Understanding (MoU) signed 1989 by several of the largest pstn operators in Europe. It prescribes a common implemenation of isdn. The itu specifications leave alot of implementation specific settings. Instead of each operator providing their own isdn specification (or that of their switch supplier) equipment would interoperate all over Europe. The standards are published by ETSI.

The ISDN primary rate interface (30B+D) is based on the G.703 2Mbit physical layer. The signaling information typically occupies one 64Kbit timeslot (timeslot 16) leaving 30 timeslots free for bearer channels.

The ISDN basic rate interface (2B+D) is based on the 2 wire "U0" interface for the link from the exchange to the subscriber premises (NT1). Within subscriber premises the 4 wire "S0" interface is more common. Variant specifications exist for the "U0" interface (2B1Q line code), namely "UK0" (4B3T line code) & "UP0" (TDMA based link local to German industry).

DOSCH&AMAND Services

• Object Code Supply
• Integration into OEM products
• Adaptions to HW, SW, OS
• HW Driver
• Product design with VoIP
• Validation

recommended module and drivers for

• Infineon IPAC NT and TE mode
• Infineon ISAC NT Mode