I have noticed a new collection agency listed on my credit report named Park Dansan. They are also a law firm and go by the name SOUTHEASTERN CREDIT as well. Neither names are registered in the state of california. I may be wrong, but aren't they required by law to be registered in each state that they do business?
Unfortunately collection agencies do not have to be registered in SC. However, if they do not have a registered agent for the service of process (if you are suing them), the Secretary of State will accept it and make sure they receive it. I think it all depends on the state in which you live - some require them to be registered - some dont.
If no registered agent in your state - serve your state's Secretary of State (that's one of the reasons he/she is there). The Secretary of State will then charge you a nominal fee to track down and actually serve the company. Call the S-o-S's office and ask if they offer that service.
If you are asking if collection agencies are required to register or be licensed in Cal. the answer is no. The link below not only gives accurate SOL's but also gives each State's requirements for CA's http://www.edebtnetwork.com/content/collection_laws.asp