Sim card is not detected by module-808

I am working on an IOT project that is "Gesture recognized wheel chair for physically disabled", in this i am integrating a GSM module-808 to get the current location of the user.
For this i have connected the GSM module with the arduino UNO with the necessary codes, but i am not getting any network connection on the board to send the GPS location to the recipient's number via SMS when i insert the sim into the slot. What to do? Please help out!