It is certainly possible to do it, but a standard NodeJS http server would not be advisable as it uses tcp. You want to use UDP as a transport layer for audio, since it will be faster and the small packet loss that can occur will most likely not be a problem.
To be completely honest with you it sounds like you need to write a few demo applications on the native platforms - so do not use phonegap. You need native platforms in order to access things suchs as the mircrophone and to stream over UDP.
When you have a demo working, you can go on and try with another platform afterwards, but start with a simple setup instead of trying to do it all at once - if it was that easy, someone else would have done it before you.
Let me recommend a simple UDP server in whatever language you are most comfortable with such as (NodeJS, Java, C, C++, C#). Let the UDP server receive and save the content into a file that you can then play back on a desktop computer to verify the result. As a simple client, build one either on Android or iOS, and stream a file that you have already recorded and included in the app. When you have this setup working, you can try to capture the microphone, then do a user interface, then support multiple phones, then build a server which records the conversations, then build a user database, and so on a so forth. But start with a prototype of your main feature.