Legal Question in Credit and Debt Law in California

If the process server left a phone number, call and make arrangements to accept service. You would then have 30 days from the date of service to file a written response with the court -- usually an answer or demurrer. Remember that there are statutes of limitation that prevent collection after two or four years of incurring the debt or of the last payment, whichever is later, so you might not want to say anything about the debt to the lawyer for the collection agency until you've spoken with a lawyer whom you have chosen.