[pchelpers] Re: Modems and mobiles

Hi John!

In message mid:3E358F4C.37A5CE62@xxxxxxxxxx 
on Monday, January 27, 2003, 1:58:04 PM, you wrote:


JD> That might have some meaning for digital phones, but analogue ones
JD> aren't usually equipped with a device to turn serial data into a
JD> modulated analogue audio signal to pass data. A minor point. Maybe we
JD> need a telecom technician's input here.
JD> PcCowboy wrote:

>> Now you all got me scratching my head. If a modem is just basically
>> a phone without a handset and dialpad. How call a cell phone have a
>> modem?
>> Wouldn't that be like a phone having a built in phone?
>> Educate me

A phone is a communications device intended for use by people, while a
modem is a communications device intended for use by computers.

"MODEM" is short for "MOdulator/DEMODulator", and it's exclusively for
analog phone lines. Cable, DSL, and satellite "modems" technically are
interfaces or adapters, not modems, as I understand it. Note that ISDN
is an old type of DSL.  Adapters are available to allow modems to work
with digital phone lines.

Back in the stone age of computers, there used to be 110-300 baud
acoustic modems. At the time AT&T owned all phone equipment (in most
areas, anyway), and there were no modular connectors. To have your
computer talk to another computer, you'd pick up the telephone handset
and push it down into the cups of the acoustic modem. Since you had
electrical pulses converted to sound by the acoustic modem, and the
phone was converting the sounds back to electrical pulses, it wasn't
possible to get much speed; I don't think acoustic modems got past
1200 baud by the time they died out.

Most modems bypass the telephone entirely and connect directly to the
phone line.

Most modems nowadays are full-featured, with FAX send/receive
capability and with voice playback/record capability.  Some also allow
switching between voice and data, and apparently some allow data and
voice at the same time; presumably requiring the handset to be plugged
into the handset jack on the modem.

This site is interesting: apparently acoustic modems aren't dead:

http://webcenter.independenttraveler.aol.com/travel/resources/article.cfm?AID=74&category=3


This site has several cellphone/modem products:

http://www.connectglobally.com/mobileandwireless.asp

-- 
--Scott.
mailto:Wizard@xxxxxxxx


Regards, John Durham (list moderator) <http://modecideas.com/contact.html?sig>
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