Re: usb modem dialing process

[Dan Williams <dcbw redhat com>]

On Mon, 2011-04-04 at 01:35 -0700, roman10 wrote:
> Can anyone help to explain the modem dialing process in network manager?
> Assume the modem is already switched to modem mode. 
> Based on what I know, 
> 1. Identify the serial port number to send AT commands.
> 2. Send AT commands to dial the modem
> 3. interface with PPPD to handle the communication. 

That's more or less correct.  Except that many modems these days don't
use PPP, they expose a pseudo-ethernet port that's used for data
communication and looks just like a real ethernet card.  You send
various manufacturer-specific setup commands to the modem via the serial
ports, and then magically the pseduo-ethernet port starts transmitting
and receiving data.

In step (2) there's a lot more that goes on too, like finding out the
access technology being used (GPRS, EDGE, UMTS, EVDO, etc) and getting
network registration status.

Dan