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Page 706 of 1536 Chapter 3 — DPNSS1/DASS2 features description and implementation
Service Independent Strings
Service independent strings are strings of data sent over ISDN links
indicating activity in progress. These strings contain data relating to
miscellaneous information that may be required during the set up and use of
other features e.g. class of service, queue information, passwords. The
following group of user features use service independent strings:
Auto Answer
Indicates that answer has been generated by the called terminal equipment.
Busy Information
Indicates which features may be used after calling a busy extension:
— call offer
— intrusion
— call back
— call back messaging
Class Of Service
The A parties class of service controlling:
— Route restriction
— call barring
— Access to facilities
DASS2 Service Indicator Code
A DASS2 service indicator code may be passed within a DPNSS1 message.
Normally for calls to or from DASS2.
Device Identity
Identifies a destination address if Originating or called line identities do not
achieve this.
553-3011-315 Standard 10.0 May 1999