Why would you think they need to be registered in California? As long as you have a valid address they can be served at you should be good to go. TCPA lawsuits should be handled in Federal Court. This web site lists lawyers who will be glad to help you out in this matter. http://www.consumeradvocates.org/
A quick check shows that they are not registered in Nevada as required by law nor are they registered nationally as a reverse mortgage lender.
Federal court requires a lawyer. Small Claims court does not but they require one to follow legal specifics. By setting up an appointment I determined it is Jesse Carlson DBA Pathways Financial Group in Orange County Reg #20126292058.