GR-303-CORE The following requirements on status and control of the overall RDT and IDT may also be used during service assurance (e.g., placing out-of-service for maintenance purposes). Placing an RDT out-of-service means stopping it from providing access services to the customers. It does not mean cutting off communication with a managing system (eg, ZMS) that controls the RDT. R5-20 [272] An RDT shall receive from a remote managing system (eg, ZMS) and process requests to place the RDT out-of-service or in-service. An RDT shall confirm with the managing system before executing the request to place the system out-of-service. R5-21 [273] An RDT shall receive from a remote managing system (eg, ZMS) and process requests to retrieve the servic status of the RDT (in or out of service). Valid values are InService and OutOfService. When an Interface Group is in outOfService state, it is removed from the GR303 protocol stack and is no longer installed on a specific card. This field is mandatory for IG row creation.