If I understood your question correctly, you want to have a secure network connection to carry encrypted communication data over it.

If you check the link here:

https://www.ringcentral.ca/technology/security.html

Ringcentral does have an end to end srtp protocol providing encryption between all the endpoints and provides transport security layer (TLS)

Also this link had a similar kind of queries with message encryption:

https://forums.developers.ringcentral.com/idea/1284/encrypting-ringcentral-sms-messages-to-external-mo.html

Which has a valid point saying that sending an encrypted message to an external application requires an authentication to decrypt it . A custom application required that need to be installed in both devices from where message is flowing that can encrypt and decrypt in both endpoints and can be integrated with ringcentral APIs hiding the data while ringcentral voice already have encryption features mentioned above.

Answering my own question -

Yes, encrypting messages before they're sent is possible but wasn't quite what I was looking for. After taking a deeper dive into the documentation and working with the amazing developer advocates I discovered the Engage Digital platform, which has support for both Facebook Messenger and WhatsApp!

https://developers.ringcentral.com/engage/api-products/digital