Garima,
There are several ways that you can accomplish this...
If you must use RightFax, then I think that should be possible. RightFax has a Web Services API, which I assume is a JSON-based REST API, which you should be able to invoke via a Genesys Cloud Web Service Data Action (https://help.mypurecloud.com/articles/about-web-services-data-actions-integration/). You can easily invoke a Web Service Data Action from your inbound call flow.
You could also use Genesys Cloud to send that outbound fax. For that it would also require using a Data Action, but this time it would be a Genesys Cloud Data Action (https://help.mypurecloud.com/articles/about-genesys-cloud-data-actions-integration/). The Genesys Cloud Data Actions allow you to call Genesys Cloud APIs and you can call the POST /api/v2/conversations/faxes (https://developer.genesys.cloud/api/rest/v2/conversations/#post-api-v2-conversations-faxes) request to send that outbound fax. The good thing about doing this from within Genesys is that conversation will also be tracked in the conversation history for the External Contact.
I can think of a few other options, but those two are the most command and straightforward ways to accomplish your goal.
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Jim Crespino
Senior Director, Developer Evangelism
Genesys
https://developer.genesys.com------------------------------