The 1231 will not work without any Antenna attached, so this is not really advisable :)
Q. Can the radios be damaged if they are operated without the antennas attached?
A. Some radio equipment manufacturers specifically warn against this because it damages the transmitter. Most pieces of amateur or commercial radio equipment carry this warning because they operate at a much higher transmitter power. The reflected wave standing wave ratio (SWR) caused by the lack of a proper antenna or load can damage the final amplifier stage known as the power amplifier (PA).
For Cisco Aironet equipment, the transmitter power output is 100 mW for the 350 series and 30 mW for the 340 series, so damage is unlikely but possible. If you absolutely have a requirement to run the devices without antennas, it is recommended that you turn the transmitter power down to 1-5 mW or use a 50-52 ohm "dummy load," just to be safe.