You could give messagebird a crack (https://www.messagebird.com/en/sms/). Within Mendix there are also a couple of modules you could try (https://marketplace.mendix.com/link/component/116784 is one). Otherwise if you're working from a mobile app, I've had success with "send text message” from the Nanoflow commons.
there are multiple modules in the marketplace that could help you with this request. For example: