Hello Brendan
Apologies for inconvenience. TCR is a text messaging compliance mandated by carriers for local phone numbers. In short, if you want to use local phone number and want to send texts to US terminating numbers, you would need to register those phone numbers with TCR via RingCentrals' Admin portal. It's a self serve registration and a simple 3 step process (Register your brand, register your campaign and link your phone number to that campaign).
Here are few support articles that can help answer your questions in detail.
Overview and Video - https://support.ringcentral.com/sms-registration.html
Setting up TCR - https://support.ringcentral.com/article-v2/Setting-up-TCR-registration-assigning-numbers-to-SMS-campaigns.html?brand=RingCentral&product=MVP&language=en_US
Associated Fees: https://support.ringcentral.com/article-v2/TCR_registration_fees.html?brand=RingCentral&product=MVP&language=en_US
TCR FAQ - https://support.ringcentral.com/article-v2/TCR-business-registration-FAQ.html?brand=RingCentral&product=MVP&language=en_US
Regards
Gurpreet Singh
PM, RingCentral Inc.
