8.5. Class of Service Switch-Over COSX 
Each terminal port is assigned two classes of service (COS): one COS comprising basic
classmarks (COS1), and one comprising alternative classmarks (COS2). When a
terminal is placed in service, the COS pointer always points to COS1; these should
be the
higher-level classmarks. On switch-over to the alternative classmarks the user receives
a
special dial tone when he picks up the handset.
LCOSV (Least Cost Routing Voice) and LCOSD (Least Cost
Routing Data) follow this same logic with LCOSV1/LCOSV2
and LCOSD1/LCOSD2.
A COS contains all classmarks for all services. These are entered
with the AMO COSSU. The COS is assigned to the port and hence to all
connected devices. This includes service-specific classmarks for FAX
and DTE. Attendant terminals are assigned only one COS (AMO ACSU), therefore,
no class of service switch-over is provided. The same is true for trunk
circuits.
Class of service switch-over can be activated:
- at the terminal
- by inserting the ID card in the card reader. Inserting the ID card, however, will not change the position of the COS pointer, but result in the automatic assertion of COS1. When the ID card is inserted in a foreign device, and provided traffic (ITR) to the reader is allowed, COS1 of the user's home port will apply.
- with a dialling procedure, provided both COSs of the user include code switch-over. The code number is assigned with the AMO PERSI. One port may be allocated several COSXCDs. The class-of-service switch-over code (COSXCD) to COS2 can be enabled for any user by setting the PERSI parameter COSXCOS2.
- from the attendant terminal
- from the service terminal with AMO BERUM
- separately for each port
- for a group of ports. This includes each port of a class-of-service-switch-over group (COSX group). There are 16 such groups. They are allocated with AMO SCSU / AMO SBCSU when the ports are set up. If the parameter is not provided, the port invariably belongs to COSX group 0. The AMO BERUM can be used for a selective switch-over to COS1, COS2 or to the currently inactive (alternative) COS.
- time-of-day-dependent; this always applies to entire COSX groups:
The switch-over times are specified for each COSX group and week day by way of the AMO BERUZ. Each day of the week one time entry can be made for switch-over to COS1 and one for switch-over to COS2. An additional code character indicates for each COSX group and day of the week whether or not switch-over should take place. This way time switch-over can be deactivated and reactivated temporarily without entering new time periods.Key switch equipment is exempted from group switch-over. For equipment using several switch-over variants (code switch-over, group switch-over from the service terminal or from the attendant terminal, or time-dependent switch-over) the most recent switch-over is applicable.
Exception:
If individual COS switch-over is to be allowed for COSX group members,
the parameter COSIND=Y must be declared in the ALLDATA2
branch of AMO ZAND. This will ensure that an individual switch-over will
not be accidentally "reset" by a group or time-dependent switch-over.
Individual COS switch-overs will then have to be revoked individually
in each case.