You have confirmed that your user's phone numbers are set to "Voice and Fax"?  

What "result" is showing in your call logs?

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Have had the same problem, I was told by RC support to tell all my vendors that use my fax number to set their analog faxes to a lower setting.  Well, that's ridiculous.  We have one lab that has to send faxes 4 times before they go through.  You would think they would have perfected 1950's technology by now.

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We have the same issue. When dealing with faxes from the IRS, hospitals or medical offices it is impossible to get them to change the settings on thier fax. I hear complaints all the time. 

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We are having this issue and RingCentral support told me that numbers that are enabled for both Voice and Fax can have this problem. The only sure fire to make sure your faxes get through is to create a new number and have it set as fax only. We are going to try this experiment. Of course there is additional cost for that number.

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My number is enabled for FAX ONLY - I just verified with RC. I continue to have issues with pharmacies not receiving my faxes despite a successful sent. They are the same pharmacies. I am able to receive faxes from them but they cannot receive mine. This has been going on for two years now. Ring Central has a responsibility to make its system compatible with all faxes. Some faxes (especially toll-free numbers) may have restrictions with receiving a fax only from certain area codes which makes me wonder whether my faxes are not being rerouted through a different area code. I know for a fact that at least once, the recipient stated that my fax came form a different area code. WHAT IS GOING ON?

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