[iwr]

The cheapest small-traffic solution I've found is to hook one or more phones to a PC and communicate with them via Hayes AT commands. Can look a little hacky, but once you have the box set up, you don't have to worry anymore. Switching "gateways" is the same as switching sim cards.

[vampirical]

I'm always a bit surprised this doesn't some up more often in these discussions. I used to use little serial GSM/GPRS modems anytime I needed to handle SMS, and that was while working for a voip company with lots of infrastructure in place for that kind of thing (the modems always won based on simplicity, speed, and consistency).

At the small scale spending $100 or so to have an unlimited test system seems comparable, and for large scale I'd much rather be buying a few unlimited SMS plans than paying per message. If the wireless provider supports SMS over GPRS you can do something like 30/min so you may never need more than one modem and sim. I wonder if it is just the barrier to entry, since you have to know that such a thing is possible and hunt down hardware/software to fit your needs rather than just buying in to one of these companies' pitches.

[akalsey]

There's lots of do it yourself ways to do SMS. You can also grow all your own food, but grocery stores tend to be the more popular option.

Companies choose to work with an SMS provider because they don't want to have to solve uptime, scale, and service issues themselves.

When you're small, running your company on a web server under your desk connected to your cable modem probably works just fine. Doing the equivalent with SMS might make sense at that stage, too. As you grow, your needs change.

One thing to note is that in the US, "unlimited" plans aren't actually unlimited. Read the fine print on your contracts. Carriers define a limit to the number of messages they consider to be reasonable use. It's a soft limit, so they don't immediately block or ban you for going over once in a while. But if you do it consistently, they'll start to charge for the overage.

[self]

This is what I do -- I have one cheap GSM modem attached to an Ubuntu box, and I use stuff from the gsm-utils package to both send and receive messages. My problem is that I can't keep the system up 24x7; it's only active during working hours, five days a week.

[pbrumm]

You should try gammu, it has great documentation and support for modems. Using cell phones seems spotty on whether they will support sending or not, but I think that is independent of the software.

http://wammu.eu/gammu/

also I chose to get a bigger 8 port modem from here.

http://www.bailing88.com/en/product_view.asp?hw_id=119

I definitely recommend their service.

works great with the latest kernel's and is usb.

seems to price out at about $50 a modem independent the size of the modem pools or a single.

[iwr]

This looks interesting, I'll check it out!