Adding a call feature in RoR webapp (free gift reward for the person who can help me!)

[crievinator]

Hi community!

I am currently building and testing a RoR webapplication but need some help with it. I want to add the possibility for the users of the webapp to call each other but I have some questions if this is possible.
Some specs:

- There are two types of users in the webapp. Only one type can initiate the call to the other type of users (the phone number of the receiver should be anonymous for the caller). Preferably the phone number from the caller should also be anonymous for the person receiving the call.
- It should be possible to call from a browser to the other type of user's cellphone (so the receiver should receive the call on his cellphone, not in the brower where the webapp is running). Is this possible (from browser to cellphone) or is it only possible from browser to browser or from cellphone to cellphone?

Free gift reward (via paypal or cryptocurrency) for the person who can help me out with specific information to make this possible (gems needed(redis, adhearsion, ..), etc. ) or who can bring me in contact with an experienced developer who can implement this.

Thanks!

Cheers,
Yves