It depends if the creditor has actually sold it or not.
Sometimes the original creditor "hires" a collection agency to collect on that debt. They still own the account but have simply outsourced the collections. In that case, you may be able to contact the OC and deal directly with them.
More often than not, the creditor "sells" your account to collection agency. In this event, the CA has bought your balance and they are "in charge" of it. When this happens, the OC has washed their hands of the account and will no longer be able to accept payments.