Sales and use tax were not applicable to prepaid calling cards sold by telecom providers to various resellers in New York between January 1, 1998 and March 1, 2000. However, after March 1, 2000 resale certificates needed to be obtained. In an Advisory Opinion, the NY Department of Taxation and Finance stated in the case of Crystal Telecom Corporation neither the provider nor the reseller had obtained the proper certificates and neither were paying sales and use tax. Both sides were given an opportunity to prove their nontaxable status on these transactions with the proper documents. A lawsuit could be filed by the telecom provider under the Tax Law for any tax owed and not paid by the reseller if they were unable to provide sufficient evidence of their exempt status. (Crystal Telecom Corp., Department of Taxation and Finance, Advisory Opinion No. TSB-A-02(37)S)