For those searching the forums for questions like this, I encourage you to check the Terms of Service and FAQ, which usually address your question explicitly at some point.
FAQ - MAY I USE FIRERTC TO SCAMBAIT?
While we do not actively push away Scambaiters, FireRTC is not meant in any way to be used to flood or DOS a call center, even if it is aimed at scammers. As such, FireRTC will temporarily block users that make too many calls in too short a period of time. Additionally, making calls programatically with FireRTC is also a violation of our Terms of Service. We do not want to add a CAPTCHA but we may have to if users are abusing the system.
In short, the answer is “Yes, but don’t harass them, even if they are scammers.” This is to comply with any and all US and international laws they are subject to due to the nature of the service. Please be respectful of the Service Provider’s needs when making your calls.
I know this specific question is about a year old. My answer is mainly for anyone new searching for this question.