I needed to implement an SMS alert capability with our office alarm system and our network management system to alert key personnel of issues outside office hours. I expect our usage to be low volume. I checked out the market for SMS messages. That the credit doesn't expire is a critical feature for us. I have had this running a few weeks now and its working perfectly. The delay between alarm activation and SMS notification has been less than 30 seconds or so. Works pretty well. The alert feature when our credit is low will be useful to enable us to top up our credit before we run out. They were easy to do business with.