EC25 module not able to connect to LTE/4G

I am using EC25 module for sim internet and working on linux version 4.4
but problem is when we tried to make connection up that time it stays is connecting state only,
We tried to make it using AT commands as well then it behave like,
1.connecting state 2.registered and connected 3.disconnected
now we are not sure how it is directly disconnected
Can you help me with this?

Hello Amol_Chavan, thanks for your question
Can you describe your problem clearly? What kind of business are you doing? You can provide us the AT command procedure, thank you.