ZyXEL Communications Omni 288S - Manual (Page 85)

Chapter 10 - Voice Mode Operation
10-6
Voice States and Operation Modes
The Omni 288’s Voice Mode DCE control interface adheres to the TIA TR29.2
committee IS-101 Interim Standard. ZyXEL is continuously enhancing its
modems' voice capability and voice feature implementation. Please refer to
future manual amendments or firmware release notes for updated details.
In ZyXEL Voice Mode, three states exist that correspond to the flow direction of
voice data between the modem (DCE) and the computer (DTE). These are
outlined in the table below.
Voice State Data Flow Direction
Voice Command State No data transfer other than event reports
Voice Data Reception State Voice data transfer from DTE to the DCE
Voice Data Transmission State Voice data transfer from DCE to the DTE
Note: Voice data DTE/DCE transfer is half-duplex.
The DCE may issue event detection reports at any time, regardless of the DCE
state. These reports may be tone or cadence events such as calling tone. ZyXEL
provides the Service Level C Event Detection Capabilities of IS-101 as follows:
Event Description DCE Voice State
RING Command
Ringback Command
Fax or Data Answer (e.g., 2100 Hz) Command
BUSY Receive, and Command
DIALTONE Receive, and Command
DTMF Received Receive, Transmit, and Command
Fax Calling Tone Receive, Transmit, and Command
Presumed Hang-up (SILENCE) Time-out Receive
Presumed End of Message (QUIET) Time-out Receive
Mandatory Receive Buffer Overrun Receive
Mandatory Transmission Buffer Underrun Transmit
Voice Command State
The DCE is in the Voice Command State and is ready to accept commands when
the DCE is operating in voice mode. Additionally, the DCE must not be
communicating with a remote station, or with any local devices capable of
translating analog signals to voice (e.g., speaker), or voice signals to analog (e.g.,
microphone).
The DCE considers data transfers from DTE commands and returns responses
back to the DTE after processing these commands. While doing so, the DCE also
monitors the line which connects the DCE to remote stations or to local devices to
detect events. The DCE later reports to the DTE, signals carried over the line,
such as tones, as well as PSTN generated control and notification signals, such as
ringing.