We integrated RingCentral API to our Java backend application to send Fax and SMS. We are getting errors when trying to send SMS.
Can you check the link and verify if something similar has not happened
Using the RingCentral Phone for Desktop, you can dial or receive test calls, send and receive test SMS or Fax messages in your sandbox environment.
Download RingCentral Phone for Desktop:
Tip: switch to the "sandbox mode" before logging in the app:
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