The only thing I have found to do is, go online into our account, as the ADMIN, and BLOCK the numbers from all our extensions.
If you do it from just one extension, it blocks the number from this extension ONLY, and you want the calls to stop at ALL extensions. It must be from the ADMIN login. follow all steps and press APPLY when done.

---

Our company has the same problem for more than 10 years, I always make a complaint to ringcentral but its technical support agents do not know and do not give any help on how to solve this great problem. Many times when we put the advertising of our products on television, radio, press or internet that coincides with the inputs of the robot calls it is extremely frustrating for the seller since he loses his turn in the line of answering calls from our advertising, for answer incoming calls from robotcalls. Please excuse my bad English.
I hope that with this you have your own conclusions of the service, which unfortunately provides ringcentral!

---