Disclaimer: I never dealt with any SMS projects.
However, the built in SMS module works with SIPStation only. After Sangoma acquired Digium they added Digium phones under the free EPM and PhoneApps version. Will they do now the same with VI and SMS?
Also, I’m not sure who your provider is, but popular providers like Twilio allow you to do SMS integrations/development directly with their platform, and there’s tons of online guides how to do it.
A recent one I saw, setting up Twilio SMS with your internal slack channel.
Note: I do not have any affiliation with Twilio.