why don't you use a GSM modem connected directly to your Hobbit server? Then you can use a software SMS-Gateway like kannel and send out your critical alerts via SMS.

Our hobbit server is not running on physical hardware. It's a virtual machine within a cluster.

At any one point, the VM is running on whatever node the cluster manager has decided it will run best on. That computation is performed every five minutes (if I remember right). Our cluster isn't heavily loaded, so the VM doesn't move around more than once every few weeks - but, that still means that if I wanted to use a physical cellular modem, I'd have to install one on each node in the cluster or get one of those new shiny cluster i/o aggregation devices which would be cost prohibitive.

We decided to virtualize hobbit for several reasons: a) Our network is not so large that we needed a dedicated server for hobbit performance. b) We're paying Southern California rates for power, so dedicated physical servers are kept to a minimum. c) We actually find apps running on our clusters to be more reliable and less maintenance than those running on physical boxes -- and, we like hobbit to be up all the time. d) We have a lot more spare computing/network capacity in our cluster than we have anywhere else. e) When making major changes to hobbit, we can just snapshot the VM before hand and if all goes to hell, we can just restore the VM snapshot to return all to working order.

Honestly, other than the SMS hardware issue, we haven't had any problems at all running Hobbit under VMware ESX.

We do have a 2nd outside-the-network monitoring system that double checks critical systems, hobbit status, and cluster status, but we'd be running that anyways regardless of whether hobbit was virtualized.