| 摘要 |
A device and a method for processing voice, data and facsimile calls in a modem is described. When the modem receives a telephone call from a caller, it answers the call and sends back a modified ringback signal having a cadence and tone similar to those of the standard telephone company ringback signal. In a preferred embodiment, the initial tone burst of the modified ringback signal has a duration slightly longer than that of the standard ringback signal. If the calling device is a data modem or faxmodem programmed to communicate with the modem of the invention, it will recognize the modified ringback signal as a dial tone. The calling device is programmed such that if it receives the dial tone, it will transmit an identifying DTMF signal to the modem of the invention. After sending the modified ringback signal, the modem of the invention waits a predetermined period of time to identify the caller. If a facsimile calling tone, an identifying DTMF signal, or a European data modem calling tone is received, then the call is processed appropriately. If no signal is received after the predetermined period of time has elapsed, the call is processed as voice. During the wait period, a voice caller receiving the modified ringback signal will assume that the call is being processed and will not terminate the call.
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