Tinysine SIM900 GSM shield message receiving issue

Greetings, everyone! I brought my Sim900 GSM shield from tinysine official website. I connecting it with Arduino Uno R3 board, I am using their original GSM library & their example coding (SMS) which are provided by tinysine. it works fine when I send a message to the Arduino. But when I want to send a message to my handphone, it doesn't send message to me even it display on my serial monitor that message was already send to my phone. Please help me, any reply would be appreciated :)