Cell phone was charged off 10 years ago and doesn't show up on the credit report anymore. Somehow the collection agency found phone numbers and updated address. The collection is $700. Not showing on the credit report anymore since is over 7 years old and can't find any old credit reports showing the date of last payment. The statute of limitation is 4 years for CA. The last message left is that the collection agency is going to file a judgement. I could easily put its time barred and exceeds the statute of limitation for CA but don't have proof. Should I write the collection agency to send the document copies of their files to prove this claim? If I had a credit report, I could prove that it is time barred.

Ok first "charged off" is an accounting term and has no bearing at all on the question. The SOL, and the last date of payment.

Also you merely inform them not to contact you further, and if they try to go to court it will be their issue to prove that it is within the SOL.

Now they can legally bill you and bill you and bill you, Unless you filed bankruptcy the debt does not just go away, so they can bill you the rest of your life, since you owe the money, but after the SOL they just can not sue you any longer