Is it possible to configure Notification Server to send SMS TEXT messages?
Yes, this is possible; however, you will need to use a third party Gateway software since Notification Server does not have this functionality built into its code. Basically, you need to have a text-interpreter, which is an Email/SMS-Gateway running on certain mail-addresses that will send text as SMS to the right number. This also works the other way around if the Gateway can handle it.
So in the Email-address field of Notification server should be something like SMS.<phone number>@altiris.com.
The mail server will hand over the sms.phone number to the SMS-Gateway (can even be an old mobile phone with the right software on the server). This gateway will send out the email as SMS to the phone number.
Most likely you'll find SMS-Gateway Software on Unified Messaging Software Vendor's pages or Call-Center Software sites.
UMS-Vendors, like Cycos, Tobit, Ferrari Fax or others. The site http://www.cycos.com/ is a German company that provides such products.
Oxygen offers a free trial at http://www.oxygensoftware.com/products/gateway/index.shtml.