Finalsite has a list of default carriers that can be used to send email-to-SMS messages. Each of these carriers has the ability to send an email to an email address unique to the person's phone number (usually in the format: [firstname.lastname@example.org]), which is automatically converted into an SMS message.
These carriers can be seen by going to Site Manager > Site Administration > Site Modules > Alerts.
To enable (or disable) any carriers
Check (or uncheck) the box next to the carrier.
Click "Update This Module" near the bottom.
To add a new carrier
Scroll down to the bottom of this view to the "Add new Mobile Phone Carrier" section.
Carrier Label: Enter the name of the carrier to add.
Carrier Address: Every carrier capable of email-to-SMS message has a unique domain they use. You can look up the specific domain for a carrier here. If you cannot find the carrier you want to add in either list, you may have some luck Googling "[the carrier] email to sms domain". When you do find the domain, enter it in here, without the @.
Number Prefix: Some carriers will add a set numerical prefix to their addresses, as in the example below. If your carrier does this, add that number here.
Country: Select the country this carrier operates in.
Once this is complete, just click Add Carrier to enable it for email-to-SMS messaging.