In the US a lawsuit is unneccessary. Simply inform the creditor that you wish to resolve the matter through written correspondance (snail mail). If they call back repeat the above, but this time add that further attempts to collect this debt over the phone will result in you filing a harassment petition with the Federal Trade Commission. That usually puts an end to the phone calls, but if you don't actually address the issue the creditor will simply sell the debt off to somebody else. Your debt goes up and then somebody else calls you. Then you have to repeat the whole thing.