Analisis Penggunaan SMS Broadcast sebagai Medium Komunikasi Pemasaran (Studi Kasus : Penggunaan SMS Broadcast pada Divisi Product Prepaid Marketing PT. Excelcomindo Pratama, Tbk) = Analysis of SMS Broadcast Usage as A Marketing Communication Medium (Case Study: SMS Broadcast Usage on Product Marketing Prepaid Division at PT. Excelcomindo Pratama, Tbk)