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Restart Indicator
The Restart Indicator information element identifies the class of the facility
(channel or interface) for restart. The Channel Identification information
element must be included with the Restart Indicator to indicate which
channel is to be restarted.
Transit Network Selection
The Transit Network Selection information element requests a transit
network for call routing.
User-to-User
The User-to-User information element conveys information between users.
The content of this information element is fully defined by users only and
has no predetermined use. The information is not interpreted by the network,
but rather is carried transparently and delivered to the remote user(s).
Locking shift to codesets
The locking shift to codesets procedure uses a Q.931 information element to
indicate a new active codeset is in use. The specified codeset remains active
until another locking shift information element is encountered. All
Q.931-defined information elements are codeset 0 (active by default).
The following codesets are defined:
Message functions
The definitions of the Q.931 and Q.932 messages and their information
elements are presented in the following tables.
codeset 0—Q.931 information elements
codeset 5—information elements defined for national use
codeset 6—information elements specific to MWC; delivers proprietary
information
codeset 7—information elements specific to the end user (for example,
customer premises equipment, regional Bell operating companies). Data
transported in codeset 7 travels across the network without
interpretation. Transport of codeset 7 information from ISDN user to
ISDN user by way of a single DMS-250 is supported for all calls.
Codeset 7 supports all 256 information elements (#00–#FF). Table
ISDNPARM is used for all supported messages on PRI originating and
terminating agencies. The messages can be datafilled as Access
Transport Parameter (ATP) or Block (BLK) for Codeset 7. The MAP
option is not valid for Codeset 7.
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
Message structure and function 4-7
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