| 摘要 |
<p>A system and method for transparent determination of call service options in a wireless communications system. The present invention initializes a call as a voice call by default. Detectors are then put in place for detecting tones specific to facsimile and data calls. If a facsimile or data call is detected, the call is renegotiated as a facsimile or data call, respectively. If a facsimile or data call is not detected, the call is maintained as a voice call. The detection of facsimile tones may be performed at the call origination side and at the call termination side. The detection of data tones can only be performed at the call termination side. For detecting facsimile calls, a called tone detector is implemented at the call termination side and a calling tone detector is implemented at the call origination side. The called tone for a facsimile machine is a combination of a 2100 hertz tone followed by a V.21 signal having a 0x7e data pattern or a single V.21 signal having a 0x7e data pattern. The calling tone for a facsimile machine is a pure 1100 hertz tone. For detecting data calls, a called tone detector is implemented at the call termination side. The called tone for a data modem is a combination of a V.25 signal followed by a modem tone, a single V.25 signal, or modem tones.</p> |
