How to make XBee module interrupt/wake arduino What I am trying to do is, to have arduino in low power mode and waking up only when a packet is received and is available to be read from the buffer. 

A scenario : Zigbee XBee module is not receiving anything, arduino is asleep. Once this particular module receives any data from any other module, it makes the arduino wake up and process this packet. 

I've looked almost everywhere possible about this, and people say they do not have a 100% working solution. 

Does the XBee module produce a particular output on a specific pin when it receives data? If so, can I connect that pin to the interrupt enabled pin on arduino and with that interrupt arduino or wake it up?
do I need arduino mega for that or is the uno a good enough option?
The pin number 9 and 13 on the Xbee are DTR/RTS used for hardware handshaking. You can connect it to the interrupt pins on the Arduino and program the arduino to wake when the pulse changes. Enable the DTR/RTS feature from X-CTU and it should work. Check this for more information.