Can I use the XBEE module in a 4.2V RS-232 serial communication?

I have two calculators (algebra fx 2.0 plus) which I made communicate by a serial connection RS-232, with the cable RX-TX-GND. I wanted to use a wireless connection, so I bought two XBEE modules :), set the same speed on the calculators and on the XBEE… However, I know that the serial communication of the XBEE is basically 0/3.3V, while my calculator operates with 0/4.2V … I think the calculator can read the 3.3V as a high logical level (one), but can I take the risk of overpowering the XBEE RX (not the external power) with 4.2V?

No you can’t connect the 3V XBee to the 4V? Device. You would need to use a level shifter between the two.

You mean a voltage divider like that:

calculator TX 4,2 V–> voltage divider –> xbee 3,3 V?

By the way I am powering XBEE with 3.3V, and the RX pin with 4.2V…