Netgear AC340U (AT&T Beam) for sms messages

We purchased the AT&T Beam and I've configured smstools under linux and everything looks okay (no error messages). Although text messages are accepted by the modem, no texts show up. I've learned that some carrier's mobile data sim don't support text. We have the sim that came with the box we ordered from AT&T. AT&T is clueless and transferred me to netgear support.

Does anyone have a suggestion where I can get a carrier/plan/sim that will work with the AC340U and text messages? I would prefer a plan rather than a pre-paid card that I have to re-fill. If you suggest a carrier, what magic words do I need to speak to have them order the right thing?