Hi Nick,

The only way to send faxes with different caller id or even fax number is to authenticate the app with different users/extensions, provided that the users/extensions were set with different caller id and fax number from the account admin portal.

You don't need to change the client id and client secret. Just the user's login credentials.

Let's say you have 2 extensions 1001 and 1002. Login the account admin site at https://service.ringcentral.com and select the user and click the Outbound Calls/Faxes tab. Set the Phone Number and the Fax Number accordingly,

Do the settings for both extensions 1001 and 1002.

When you login your app with user 1001 login credentials to send a fax, the Phone Number of 1001 extension will be the caller id and the Fax Number will be the from number.

Hope this helps!

Hi Phong,

Thank you...

This is what I expected (one client Id, many usernames) but our telephony guy here thought otherwise.

I believed he based that assumption on the Sandbox account, can it only have one username per client Id?

If that's the case then it means we will only be able to test this once we go into Production which we should be able to go into soon. For reasons shared in private email I was not able to work much on this in the past few weeks.

Thank you and have a nice day,

Nick