Note: this is a "vintage" tip for older computers/systems.
One of the important functions which computers are being used for now, and even more in the future, is communications. The current communications devices: phone, fax, etc can be replaced with a computer. In the past several pieces of hardware and software were necessary to achieve this result. The only hardware necessary to achieve this on a PowerMac is the Apple Geoport telecom adaptor cable which connects your phone system (standard analog line, ISDN, etc) to the geoport connector (either of the serial ports) in your machine. The modem is actually a program which runs in the background on the PowerPC processor.
Geoport in Use
Here's how it works (theoretically):
The phone rings and the modem answers it for you (when I say the phone rings I mean an incoming call is detected. You don't actually need a real phone any more because the computer does all that for you). The computer briefly listens to the phone to determine what kind of call it is (if there is a person at the other end they don't notice). The computer decides what to do with the call... If its a data call the software modem routes it to Apple Remote Access which allows the user to connect to the machine to transfer data, etc. It its a fax call the fax software automatically accepts the fax and stores it (and maybe uses OCR (optical character recognition) to turn it into a text file. If its a voice call and the user has clicked a button the computer becomes a "hands free" speaker phone. The persons voice comes from the Mac's speaker and you speak into the microphone. If the user doesn't answer the phone a phone answering program plays a recorded message and stores the person's response. The system hangs up the phone and waits for the next call.
The same sort of things happens in reverse when you make a voice, data or fax call out to another computer or a conventional fax or phone. If you buy extra software you can even set up a call management system which can navigate through various messages depending on the keys the person types on their phone. For example the computer might say "type 1 on your keypad to hear Owen's latest high score in Marathon, type 2 to hear what Owen did on his holidays, type three...".
So for just one adaptor cable and the software that comes with it you get all of these functions: data modem, fax send and receive, hands-off speaker phone, phone dialler, phone answering machine, phone call scheduler, phone log, contact database. The software implements features only available in expensive specialised machines like the ability to call the computer and enter a code to have it read your phone messages back to you. Because the whole thing is done in software there is no extra hardware to clutter your desk. Its Mac software so of course its easy to use (much easier than using a real phone answering machine or fax, anyway). And finally its much cheaper than buying all the individual parts.
Its not Perfect!
Sounds too good to be true? Well there are some disadvantages too - these are the ones I have found: First and most seriously, you can't fax a paper document unless you scan it first but you can fax a document prepared in any Mac program. Secondly the software doesn't seem to distinguish between voice and data calls properly every time so I need to help by switching programs on and off. For example I use the speaker-phone/dialler/phone-answerer during the day and the data modem after hours. Note that this should work, maybe in a future release of the software it will be more reliable. The data modem is limited to 14.4 kbaud in the current release (which is fast but there are faster hardware modems around). Much higher speeds are possible and remember its a software modem so only a software upgrade is necessary. Finally because the CPU does the work you do notice a slight slow down in the speed of your machine if you are using other programs when a call comes through. This is one area where a second dedicated DSP chip is an advantage.
Update: GeoPort on Modern Macs
GeoPort is no longer being supported by Apple. The GeoPort software hasn't been maintained and doesn't work reliably on modern computers. Apple haven't sold GeoPort harware for a number of years. Therefore the information in this page is only relevant for older machines that can run systems before 9.
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