Blueworx Voice Response defines the states of a channel as:
- SL_CHANNEL_STATE_ENABLED
- The channel is enabled, and can be used to make and receive calls.
- SL_CHANNEL_STATE_QUIESCING
- The channel is quiescing. No new calls can be made or received. Existing
calls are unaffected.
- SL_CHANNEL_STATE_DISABLED
- The channel is disabled and cannot be used to make or receive calls.
- SL_CHANNEL_STATE_ALARM
- The channel is in an alarm state and cannot be used to make or receive
calls.
All common channel signaling processes are expected to implement this channel
state model.
These states and the allowed transitions are shown in Figure 1.
Figure 1. Channel state model
![The allowed transitions from Enabled are: from Enabled to Alarm by SL_CHANNEL_IND (alarm); from Enabled to Disabled by SL_CHANNEL_DISABLE_IND or by SL_CHANNEL_DISABLE_REQ and SL_CHANNEL_DISABLE_CNF. The allowed transitions from Disabled are: from Disabled to Enabled by SL_CHANNEL_ENABLE_REQ and SL_CHANNEL_ENABLE_CNF; from Disabled and remaining at Disabled by SL_CHANNEL_ENABLE_REQ and SL_CHANNEL_ENABLE_CNF (fail). The allowed transitions from Alarm are: from Alarm to Enabled by SL_CHANNEL_ALARM_IND (clear); from Alarm to Quiescing by SL_CHANNEL_QUIESCE_REQ; from Alarm to Disabled by SL_CHANNEL_DISABLE_IND or by SL_CHANNEL_DISABLE_REQ and SL_CHANNEL_DISABLE_CNF. The allowed transition from Quiescing to Disabled is by SL_CHANNEL_QUIESCE_CNF.](./chanmod.gif)