@Andy Miscuk This KB should help with your question!
https://support.ringcentral.com/article-v2/Enhanced-Business-SMS-new-Price-Changes.html?brand=RC_US&product=RingCentral_MVP&language=en_US

For additional context, right now RingCentral allows you to send up to 50 messages/ min/ number currently with our standard (Enhanced) SMS solution. In general, that means a single number can send up to 72,000 SMS/day (if it sends continuously). Please be advised that once your allocation is reached (as Becky linked to above) overage fees will apply. For higher volumes we recommend purchasing a bundle to receive SMS at discounted rates.

Note TCR campaigns have their own throughput limitations based on your business, vetting, trust score, and campaign type. Most customers will not be impacted by these, but if sending higher volumes (eg 140,000 across 2 numbers/ day) please reach out to your rep and request a consultation so we can make sure you are set up for success.