Right now, we able to sent fax using single extension.
Could you please share us link that sending fax using different extension.
Thanks for your help.
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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