First things first. Depending on the size of the debt, I would suggest that either you or your attorney contact the law firm that has the debt and see if you can come to an arrangement for payment. The statute of limitations is determined from the date that you last made a payment on the account. Moreover, the statute of limitations is measured in the jurisdiction in which you reside. Debts can be based on contract and hence can have limitations as high as 10 years in some states. Debt collectors are not required to send you certified mail. They only have to send a letter informing you of your rights under the Fair Debt Collection Practices Act. They only need to send this letter by first class mail.
If your credit means anything to you, your best option is to try to resolve this debt. Remember, bad debts stay on your credit report for 7 years. Getting it resolved begin the count down on that time period.
In North Carolina, law firms are not required to have any special license to engage in collection activities. All junk debt buyers and collection agencies, however, must obtain a collection agency permit from the North Carolina Department of Insurance. You can check to see whether an agency has the proper permit at https://sbs-nc.naic.org/Lion-Web/jsp/sbsreports/CompanySearchLookup.jsp.
The statute of limitations on MOST loans and credit card debt in North Carolina is three years from the date of default (missed payment). You would have to have an attorney review your loan documents or credit card information to determine for sure if that statute of limitations applies, or if a longer one does.
Never make payment on an alleged debt without first having validation that the debt is yours and that the company requesting payment is the owner of the account. Request that the company provide you with information about the account, including the loan documents with your signature and the payment history, so that you can determine whether this account is yours. Also request that the company trying to collect provide you with proof of its ownership of the account. Ownership of account should include bills of sale that list the account name and number.
The owner of a junk debt must provide this SAME information to prove its case in court, so if it cannot provide this information to you now, odds are it does not have enough proof to win a case against you in court.
Any collection calls that include false threats, abusive or obscene language, shouting, etc. may violate state and/or federal law. You can read the North Carolina laws on debt collection here: http://www.ncga.state.nc.us/EnactedLegislation/Statutes/HTML/ByArticle/Chapter_75/Article_2.html, and you can read about the federal law here: http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre18.shtm. If you believe the company collecting has broken state or federal law in your case, talk to an attorney.
(This response does not constitute legal advice and does not create an attorney/ client relationship. The response is in the form of legal education and is intended to provide general information about the matter in question. Many times the questioner may leave out details which would make the reply unsuitable. The questioner should confer with an attorney about the specifics of their case.)