Fax limitation in number

"The throttling rates per API are determined by your RingCentral API Usage Plan and the API group for the API in question. The fax API is classified as a Heavy API which is set to 10 requests / minute by default so the fax rate is 10 per minute or 600 per hour. "

ref: https://ringcentral-faq.readthedocs.io/en/latest/fax/