> > You being a ex-telecom engineer...what's the difference between a
> > modem
> > and a line card ?
> > They are both DSPs, I suppose...is it the ability to switch a circuit
> > ?
> > My brain hurts, just trying to think how analog signals are routed.
>> Well, a modem IS a line card, of a sort, but of a specialised sort
> which enables you to extend a serial data channel over indefinite
> distances over an analog phone line.
Don't forget, a line card will also generate the -48V DC supply for
a phone, generate the ring signals (70V AC, IIRC) and, these days,
maybe even provide caller ID. And won't fry itself if the 48V supply
"Phone" sockets on modems are just pass-through connections, optionally
via a relay which allows the modem to disconnect the phone when it's
on a call.
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