IA lists AirLink RV50/RV50X, RV55/RV55X, Raven XE, LS300, or LX40 as the supported routers for SMS use. From that list pretty much all except RV50X and LX40 are active devices. Rest are either obsolete or on its way of becoming obsolete; unless Dr Google lied to me. From these choices RV50X is the easy choice to go with but it feels like I am missing something. There can't be pretty much just one option. I am wondering what are people using when using a physical cellular router.
There may be other Airlink devices that work but not ones we've tested or confirmed to work.
The problem is that this isn't a generic SMS module that works with any cellular router; it implements a protocol specific to the Airlink devices for an obscure SMS feature it happens to have.
IMO you'd be better off using the Airlink, or any other cellular router, to get you online so that you could use Twilio instead.