With the T-311 Telephone Access Unit computers can make and answer telephone calls, and information about those calls can be returned to the computer. While a modem only transmits data from computer to computer over telephone lines, the T-311 allows communication between called and calling parties.

Computer Telephony Integration

This communication is made possible by the conversion of DTMF-to-ASCII and ASCII-to-DTMF. With the T-311, computers and other terminal devices can control telephone system functions such as answering and placing calls, observing call status, sending or receiving DTMF signals, "flashing" the line, and coupling audio sources, like speech synthesizers, onto the line.

For compatibility with communications software, the T-311 uses the industry-standard AT command set. It responds to commands and call processing events by sending messages to the computer.

The T-311 uses EEPROM nonvolatile memory to store vital configuration data.

Auto-Dialer Capabilities

When used in conjunction with contact management software, the T-311 is a powerful automatic dialer. Working with the records from the software database, it speeds call completion by detecting busy/reorder tone and immediately moving to the next number. The result is increased "talk time", thereby improving the efficiency of calling agents.

DTMF/ASCII Conversion

After a telephone connection has been established, ASCII characters from the computer are converted to DTMF tones and forwarded to the network. In the opposite direction, DTMF digits entered at a telephone keypad are converted to ASCII characters and forwarded to the computer.

Telephone Line Control Features

The T-311 enables computer control of the telephone line, including the following key features:

Off-hook
The T-311 takes the line off-hook ("seizes" the line) when commanded by the computer to make or answer a call. The T-311 uses the standard ATD command to dial outgoing calls, but unlike most modems it provides full call progress monitoring.

On-hook
The T-311 places the line on-hook (disconnects) upon command from the computer, or automatically if a caller fails the security check, loop current is lost, or inactivity timeout occurs.

Ringing
The T-311 detects ringing on its incoming line. If response messages are enabled, the T-311 sends a RING message to the computer. The call is automatically answered if autoanswer is enabled.

Hold
The T-311 puts calls on hold and removes the hold when commanded by the computer.

Outgoing Call Features

The T-311 controls outgoing calls with the following features:

Autodialing
The T-311 can autodial a series of programmed numbers. It can also permanently store a number string for repeated dialing with the command "ATDS".

Tone and Pulse Dialing
To ensure the widest possible range of applications, the T-311 works with both DTMF and rotary signaling. The T-311 can detect both primary and secondary dial tones. In the autodialing mode, the T-311 can be programmed to delay dialing until it detects secondary dial tone.

Call Progress
By detecting and analyzing standard call progress tones (e.g., reorder, busy, and audible ringing ("ringback"), the T-311 is able to return information to the computer about the status of originated calls. By detecting Special Information Tones (S.I.T.), the T-311 recognizes incomplete calls to speed placement of the next call.

Incoming Call Features

The T-311 controls incoming calls with the following features:

Auto and Forced Answer
Auto answer allows unsupervised operation of the T-311; forced answer commands the T-311 to answer the call. By disabling answer altogether, the T-311 owner can ensure that the telephone line is used for making outgoing calls only.

Security Checking on Answer
When security is enabled, the T-311 automatically disconnects callers who fail to enter the correct password in the allotted time.