Well, you'll be glad to know that most IoT devices today, basic to best, comes with immense support for connectivity. The primary ones like Raspberry Pi or Arduino or Intel Edison offer the best platform for extending almost any type of feature or functionality on it, especially for all modes of connectivity. So, you could use dongles and modems with them, use their USB Ports or even add entire network boards on top of them like the GSM Shield for an Arduino or a similar Hat for the Raspberry Pi. You can also code in almost any programming language to control the actions of your SMS services.