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CX20463LSD

SmartSCM Modem

Conexant Systems 

SmartSCM Modem Data Sheet

2.8 Telephony Extensions

The following telephony extension features are supported and can be typically be implemented in designs for set-top box

applications and TAM software applications to enhance end-user experience:

• Line In Use detection

• Extension Pickup detection

• Remote Hang-up detection

2.8.1 Line In Use Detection

The Line In Use Detection feature can stop the modem from disturbing the phone line when the line is already being used.

When an automated system tries to dial using ATDT and the phone line is in use, the modem will not go off hook and will

respond with the message “LINE IN USE”.

2.8.2 Extension Pickup Detection

The Extension Pickup Detection feature (also commonly referred as PPD or Parallel phone detection) allows the modem to

detect when another telephony device (i.e., fax machine, phone, satellite/cable box) is attempting to use the phone line.

This feature can be used to quickly drop a modem connection in the event when a user picks up a extension phone line. For

example, this feature allows set top boxes with an integrated SmartSCM modem to give normal voice users the highest

priority over the telephone line.

This feature can also be used in Telephone Answering Machine applications (TAM). Its main use would be to stop the TAM

operation when a phone is picked up.

2.8.3 Remote Hangup Detection

The Remote Hangup Detection feature will cause the modem go back onhook during a data connection when the remote

modem is disconnected for abnormal termination reasons (remote phone line unplugged, remote server/modem shutdown.

For Voice applications, this method can be used in addition to silence detection to determine when a remote caller has hung

up to terminate a voice recording.

2.9 Fax Class 1, Fax Class 1.0, and Fax Class 2 Operation

Facsimile functions operate in response to fax class 1 commands when +FCLASS=1, fax class 1.0 commands when

+FCLASS=1.0, or to fax class 2 commands when +FCLASS=2 is installed

In the fax mode, the on-line behavior of the modem is different from the data (non-fax) mode. After dialing, modem operation

is controlled by fax commands. Some AT commands are still valid but may operate differently than in data modem mode.

Calling tone is generated in accordance with T.30.

2.10 Voice/Audio Mode

Voice and audio functions are supported by the Voice Mode. Voice Mode includes three submodes: Online Voice Command

Mode, Voice Receive Mode, and Voice Transmit Mode.

2.10.1 Online Voice Command Mode

This mode results from the connection to the telephone line or a voice/audio I/O device (e.g., microphone, speaker, or

handset) through the use of the +FCLASS=8 and +VLS commands. After mode entry, AT commands can be entered without

aborting the connection.

2.10.2 Voice Receive Mode

This mode is entered when the +VRX command is active in order to record voice or audio data input at the RIN pin, typically

from a microphone/handset or the telephone line.

Received analog voice samples are converted to digital form and compressed for reading by the host. AT commands control

the codec bits-per-sample rate.

Received analog mono audio samples are converted to digital form and formatted into 8-bit unsigned linear PCM format for

reading by the host. AT commands control the bit length and sampling rate. Concurrent DTMF/tone detection is available at

the 8 kHz sample rate.

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