Revenue from two licensees constituted approximately 66% of the Company's revenue for the year ended December 31, 2018. Revenue from the sale of the Company's unsecured claim against Avaya, Inc. constituted approximately 29% of the Company's revenue for the year ended December 31, 2018. Revenue from three licensees constituted approximately 67% of the Company's revenue for the year ended December 31, 2017. At December 31, 2018, royalty receivables from four licensees constituted approximately 80% of the Company's royalty receivables. At December 31, 2017, royalty receivables from three licensees constituted approximately 79% of the Company's royalty receivables.