Input voltage levels for XBee

I need to use an Series 1 XBee module to Directly Read inputs and transmit to a receiver.. I need to supply both analog and digital inputs. What are the max and min voltage levels XBee can accept? What other stuff I should concern implementing this?

Thanks.. :)

What are the max and min voltage levels XBee can accept?

Max = 3.3V. Min = 0.0V.

What other stuff I should concern implementing this?

Sensor type, current, speed...