Good question! Right now we are fortunate to have some AWS credits to subsidize some voice costs :P. At the moment our focus is on usage, but our goal is to have a freemium model based on the size of the space, premium assets, etc.
If you want to be „close” to AWS but still save money, try spinning lightsail instances that act as media proxies, similarly with other more resource generous providers. You could shift majority of media traffic off AWS and keep the “signalling” just there.