Service State

Use the Service State Configure message to bring spans into service. After you bring spans into service, you can then bring channels, signaling links, and D channels into service.

The host controls the service state of many entities in the Excel platform, including spans. When spans are initially assigned a Logical Span ID, the spans are out of service. Using the Service State Configure message, the host controls when spans and channels are brought into service and out of service.

When a span is out of service, it does not transmit valid signaling and ignores any signaling it receives (except for Loop Timing sources, where the span is enabled and framing is monitored). In either case, the LEDs on the line card are off.

When the host brings a span into service, the Excel platform enables the span to transmit signals, and begins to monitor framing. The LED indicates either red (red alarm), yellow (yellow alarm), or green (framed up).

Important! Bring channels configured for outgoing calls (or connection) into service before you bring channels configured for incoming calls into service.

The Excel platform uses the DS0 Status Change message to notify the host of channels in a channel’s state.

Do not consider a channel in-service until the host receives a DS0 Status Change message with a status of In-service. When a channel is in-service, the software scans for and responds to inseizures and may generate outseizures. Until a channel is in-service, the host does not see any Request for Service or Request for Service With Data messages for that channel from the Excel platform.

A channel that is out of service ignores inseizures, and transmits on-hook signaling according to its trunk type. To prevent false Request for Service messages from the Excel platform, take faulty channels out of service. The Excel platform automatically brings all associated channels out of service, when one of the following conditions is detected for a span:

When the span becomes valid again, all of the affected channels are brought back in service, as long as the channels were previously brought in-service by the host.

After you bring all the channels back into service, use the Tag Configuration message to assign a tag to a card’s configuration. The host uses this tag in the Card Status Report and Card Status Query messages.

The condition of a component at a given instant. The current "context" of a PPL object, such as Idle, Seizing, Answered. In PPL files, a State is represented by a circle.

Range of channels provided by T1 or E1 transmission service. A physical span is a group of channels taking up a single physical wire. A logical span is a group of channels taking up less than a single logical wire, or carried over more than one physical wire.