Solution:
· Integrated Services Digital Network
· allows existing phone lines to carry digital information
· more of a dial up service than a permanent lease connection
· Two main interfaces
· BRI Basic Rate Interface
· PRI Primary Rate Interface
Comparison of BRI and PRI Services
|
|
BRI |
PRI (US/Japan) |
PRI (Europe) |
|
Channels |
|
|
|
|
Data Channels |
2 |
23 |
30 |
|
Control Channels |
1 |
1 |
1 |
|
Data Channel Speed |
64k |
64k |
64k |
|
Control Channel Speed |
16k |
64k |
64k |
|
Bandwidth |
160kbps |
1.544Mbps |
2.048Mbps |
· B channels are used to carry data/voice
· D channels are used for call control and signaling (call set up and tear-
down)
· each B channel can support one call (digital or analog) at a time
· delivered from the telco over a single twisted pair wire
· in some places, due to poor/old equipment, data speeds may be
limited to 56k instead of 64k and only one channel is standard instead
of two.