Specifications

Dispatch Call Types
Dispatch Call Processing
August 08, 2000 68P81095E55-E 4-9
Dispatch Group Calls
Dispatch Group Calls allow MSs which are members of predefined groups to
communicate in half-duplex (one person talking at a time and the others listening)
among themselves. Only members of the group can participate in the conversation
and any authorized group member can either set-up or participate in the call. The call
can be set up without all group members being available and can involve members
being served at different sites. Any group member can leave the group at any time.
After one MS makes the request, the Fixed Network Equipment (FNE):
• Validates the Dispatch Group Call request
• Determines the Dispatch Location Areas (DLAs) of the group’s members
• Pages members (sends a Location Request) in those DLAs
• On Page response, assigns a channel at each site that needs to be added and
have resources available.
Figure 4-6 Dispatch Call Setup
If no servers are available at the caller’s site, the call is queued. If a server is
available at the caller’s site but not at other sites, those sites are included into the call
as servers become available. Pages will be sent out only in those Location Areas
where active group members are registered (provisioned). Once an MS responds to
the page, only those cells with active MSs will have voice channels assigned. After
each transmission, the FNE maintains the call for the pre-defined hang time. If the
hang time expires, the channels are disconnected and the call is torn down.
The types of Dispatch Group Calls that define the extent of the area of the call are:
Wide Area, Local Service Area, and Selected Service Area Dispatch Group Calls.
Called MSs Caller MS FNEMESSAGE
DGC REQUEST
DGC PROCESSING
DGC PAGING REQUEST
DGC PAGING RESPONSE
DGC GRANT INITIATOR
DGC GRANT TARGET
Three types of Dispatch Group Calls (DGC):
Local Area Call - communications between MS in the “Home” or “Local” service area.
Selected Area Call - communications between a caller and a group in a different service
areas.
Wide Area Call - communications between a caller and a group anywhere in the network.