Hi Jinoj,
Many Sierra product has TCP/IP stack built in with FTP/HTTP support, the session will be initiated by MCU via AT commands.
Perhaps you can check the spec for other requirements?
http://www.sierrawireless.com/productsandservices/AirPrime_Wireless_Modules/Smart_Modules.aspx
http://www.sierrawireless.com/productsandservices/AirPrime_Wireless_Modules/Essential_Modules/HL_Series.aspx
http://www.sierrawireless.com/productsandservices/AirPrime_Wireless_Modules/Essential_Modules/WS6318.aspx
Thx.