HP 8920A Programmer's Manual page 486

Chapter 8, Programming The Call Processing Subsystem
Programming The CALL CONTROL Screen
System Type
NOTE:
486
This field is used to select the type of cellular system (AMPS, TACS, JTACS)
which will be simulated.
The :CSYStem command is used to control this field.
The field is an immediate action field. That is, whenever the
System Type
:CSYStem command is sent, the change is reflected immediately in the physical
configuration of the Test Set (the control channel is immediately deactivated,
reconfigured, and then reactivated to reflect the change) and causes an immediate
change to the current state of the Call Processing Subsystem (the state is set to
).
Active
If the Test Set is in the Connect state and a change is made to the System Type field
the Connect state will be lost.
The query form of the command (that is, :CSYStem?) can be used to determine
the type of cellular system currently being simulated.
Syntax
:CSYStem <'><AMPS/TACS/JTACS><'>
:CSYStem?
Example
OUTPUT 714;"CALLP:CSYS 'AMPS'"
OUTPUT 714;"CALLP:CSYS?"
ENTER 714;System_type$