Original high speed Internet Connection
Uses POTS network system that operates via Circuit Switching
Allows simultaneously have data transfer (internet) and phone call at the same time (The internet was transmitted digitally over POTS while the telephone signal was transferred in analog)
Basic Rate Interface (BRI)
Uses two data channel (Bearer of B) that operates at 64Kbps for total speed of 128Kbps
Also had a D channel of 16Kbps for transferring control signals
Was used in households
Primary Rate Interface (PRI)
High speed form of ISDN. Was used by businesses
Uses T1 and E1 trunk lines (T1: USA, Canada, Japan, E1: Europe)
T1 trunk line 24 channels of 64Kbps (Total Speed: 1.544Mbps)
- 23 64Kbps B Channel
- 1 64Kbps D Channel
E1 trunk line 32 channels of 64Kbps (Total Speed: 2.048Mbps)
- 30 64Kbps B Channel
- 2 64Kbps D Channel