I still use and love qpage http://www.qpage.org/ with Nagios.
 
Your best bet is to also attach a modem to your system and let it dial out to the gateways.
http://www.notepage.net/tap-phone-numbers-u.htm
 
This site provides a central spot for TAP gateway numbers and SNPP systems. Use your Nagios parent configuration to send snpp when the Internet is working and fall back to TAP modem pages when your system can no longer reach the net.
 
It's the only modem I still have in use but it works great every time for sending out those text messages and pagers.
 
Derrick

From: owner-nanog@merit.edu on behalf of Randy Epstein
Sent: Wed 4/16/2008 1:22 PM
To: 'David Ulevitch'; nanog@merit.edu
Subject: RE: Postmaster @ vtext.com (or what are best practice to send SMS these days)


David Ulevitch wrote:

<snip>

> What else are operators doing to get the pages out when things go wonky?

Get a pager!  :)  SMS is just not as reliable.

> David

Randy