8-6 Dialable Wideband Service
297-2521-106 Standard 23.01 March 2001
When a SETUP message is sent over a PRI link, the message includes the
following:
• B-channel request—a request for a specific number of B-channels to be
allocated for the data transfer
The DMS-250 switch selects the number of B-channels to accommodate
the bandwidth requirements contained in this SETUP message.
• wideband call requirements, including:
— a bearer capability (BC) information element—identifies the data
transfer rate
— a channel identification (CID) information element—identifies the
individual B-channels that are grouped to form the wideband channel
When the BC element identifies a transfer rate greater than 64kbit/s, and the
CID element identifies more than one B-channel, the switch system utilizes
DWS.
Bearer capability information element
The BC, represented by a binary code, is located in the information transfer
rate field of the BC information element. The code for MWC is compliant
with the UNISPEC/NT.
Channel identification information element
The CID information element identifies the channel(s) to be used in the
wideband call, the type of interface, the coding standard, and the channel
type (B, H0, or H11). If there are no protocol violations, the DMS-250
switch reads the CID information element to allocate the channels indicated
in the CID information element. Figure 8-4 shows the fields contained in the
CID information element.
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