At the SMS gateway details page you can setup your SMS gateway.
The settings form:

The settings form is used to setup all necessary settings for your SMS gateway.
Please note: Depending on your sms gateway provider these settings may vary.
Typically, you will need at least to setup a username and password, the protocol to the SMS gateway and the URL to the gateway. If the URL to the gateway field is left blank, the default URL for the selected SMS gateway provider will be used.
The name field is only used internally by the shop software and can be changed to identify your various gateways (e.g. If the service is provided by a subvendor of the gateway provider).
Click on the “Save Changes” button to save your SMS gateway settings.
Click on the “Back” button to return to the SMS notification setup page.