Notifications by SMS

What are the recommended ways to have Nagios send SMS notifications via the net? (Non modem solutions please.) Free and non-free.

TIA,
Chakatz

I didnt install any packages. I just used the email version of my cell phone for example [email protected] you might be able to just put your phone number in from of @message.alltel.com in your contacts. But I am still trying to shorten the notifications so that it doesnt send me two text messages each time a server goes down

o yah and i dont have a modem, and its free

I use aql its not free you buy text messages in bundles, however you can setup a distribution list to msg a number of mobiles which is cool and very easy to setup as its technically just an email address.