I had a bit of struggle to understand precisely how this works. I haven't had a need to use similar technology...But at least one mechanism seems to be:

1. Data submitted by end user

2. Intercepted by an Evervault Server and encrypted

3. Hits my Application where I utilize the encrypted data without being able to see it

4. Submit it to some other service (Twilio say)

5. Relay intercepts request and decrypts required fields before data is sent on to Twilio.

6. Presumably response from Twilio is also encrypted? Or it's optional?

I'd be interested to hear from anybody who has implemented these kinds of flows to better understand uses cases and the complications etc...