May minh 4S Verizon xai sim ghep R-Sim. Moi khi co tin nhan den la tieng chuong bao bi lap lai nhieu lan ( no keu tieng dau tien cua chuong bao lien tuc nhieu lan roi moi keu het doan chuong) .Co khi bi treo may 1 luc moi vao duoc .Ai bit cach khac phuc chi dum minh nha. Thank!