KennyR wrote:
(Trying not to go into a rant about how USB is totally unsuitable for modems and how manufacturers who do this should be sellotaped to a large weight and dragged through a cheese grater factory by a camel.)
USB is perfectly suitable for conventional modems, and,
technically, wouldn't be bad for broadband modems.
Now, here's the way it works out in reality: Conventional USB modems are usually 'winmodems' (effectively a USB soundcard), and if you get one that does adhere to a standard, you're still stuck fiddling with your OS (if not Windows) to make sure it supports 'ACM' devices, the 'Abstract Control Model' basically being the way to use USB like a... plain old serial port (bytes go in, bytes come out, nothing much special happens).
Broadband "modems" aren't really 'modems' (well, they are to the same extent an ethernet card is). Because of the performance issues involved (or maybe just for braindeath), nobody's really bothered to try to think of them as modems. To make matters worse, there's no one standard for doing "network-like things" over USB, so each broadband 'modem' is doomed to be different. Making things more fun, while just about any protocol can be run over the DSL 'wires,' telcos usually choose to use ATM (just in case they want to enable ), and let 'modems' with an ethernet port bridge to ethernet frames at the user end.
Is that horrible? Well, not really, except no "normal people" use ATM, so even if you can get data back and forth from the USB 'modem' -- doubtful unless you have a proprietary driver -- your OS may not come with support for decoding the ATM frames and doing something useful with the data (IP or PPP, and if the latter, not only do you have to be able to 'read' the ATM frames, you have to be able to shove the data from them through your PPP handler) within.
That last part is, technically, an 'All the world's a VAX!' problem on the OS's side (assuming all the world is ethernet or ethernet-like), but do
you feel like coding up ATM support for fun? Thought so.
So... In practice, to make a USB DSL 'modem' work, you generally need
both:
-Cooperation from the hardware vendor, to get or allow-creation-of a driver for the device in the first place.
-ATM support in your OS that will work with said driver and do what you want it to do.
One or the other won't cut it. Thus, you may have a
snowball's chance of making something work on Linux/i386 or OS X, but anything 'stranger' and all bets are off.
Edit: I just noticed that Poseidon has a cdcacm.class for using USB modems. Give that a try!
This is only useful for 'conventional' modems, though there may be a few ISDN devices that follow the same methodology. Generally, the only things using this class will be things that used to have a RS-232 port on the back of them.
My modem that I got with Blueyonder has both USB and ethernet - the ethernet will work.
Because all these little headaches haven't been solved in the world at large, pretty much everyone everywhere continues to focus on ethernet support (hey, it's needed to, er, use ethernet, anyway), and because roughly every single person who would have otherwise tackled the problem has shrugged and gotten an ethernet modem instead, it's likely to stay that way for quite some time.
Moral of the story: If you want it to work this decade, yes, go with an ethernet model!
[PPP-over-Ethernet actually has its own small problem (itself the ripple effect of another 'small problem') that PPP-over-anything-but-Ethernet probably wouldn't --
see section 6.3.1 of this link -- but pretty much every home router on the planet now handles this for you.]
Although...you can get routers with USB ports for modems. A good choice to get online with both your Peg, A1 and PC all at once.
I believe there are a few of these out there, but given the above, make sure they actually support *your* model of modem before you dive in. It's far more common to see USB as an option to go from router-to-PC (in case you don't have an ethernet card in your Windows machine), and if there's any question, it's usually just as cheap these days to get a router with a general-purpose DSL modem built in.
