Is it possible to send SMS messages from the command line using SMS Server?

Yes, that’s possible. You can use the API of the SMS Server to create a quick script that can be run from the command line.

You can script using Powershell, JavaScript as well as VBScript.

To find simple samples that can be used to get started please have a look at the samples directory:
C:\ProgramData\Auron\SMS Server\Samples\Api\Vbscript