There are no per se DTMF recievers on the 8100/UX5000 systems they use DSP resources on the CPU. I suspect a glitch, Try Shutting down , pull the CPU and let it sit in the slot but not pligged in for about 5 min. so the caps will discharge.

There are some settings in 10-09 for allocating the dsp's but at default the first 8 are set for analog extensions, the next group 9-32 are for trunks, and the last group 33-160 are for extensions and trunks.

DJ