Not sure how you chose the number but it seems the phone number does not have SMS cap.

There are lots of discussions about most of the topics/errors you have been asking here. You can always search from the forum to get solutions before posting your questions. Or provide better background info of how you send SMS.

Search for "MSG-242 error" to see previous discussions.

You can check same issue posted here already as reference: https://community.ringcentral.com/questions/9704/reg-msg-242.html

https://community.ringcentral.com/questions/9693/send-sms-in-production-msg-242-error.html

https://community.ringcentral.com/questions/10464/msg-242-feature-not-available.html

https://community.ringcentral.com/questions/90055/sending-sms-in-production-account-msg-242-error.html

https://community.ringcentral.com/questions/1188/sending-sms-using-api-gives-error-code-msg-242-the.html

https://community.ringcentral.com/questions/11212/im-getting-error-message-msg-252-featurenotavailab.html