@beavis , You have a limit of 50 calls per day on FireRTC, but avoid making a lot of calls in a short period of time. As long as you don’t do those two items, being locked out should not be a problem. Avoid autodialer programs and just keep an eye on how many calls you make.
As far as tracing your IP address, they cannot unless you actually allow them to connect to your machine, or a VM. Just using FireRTC to call them will not give them anything to work with. That being stated if you actually allow them to connect to a machine, it is wise to use a VPN .
I actually had one call me this morning and was able to keep him on the phone without even getting near my computer. Just play really dumb, and drag out the conversation as long as possible. Every minute of their time you waste, stops them from calling someone else.