Yes, there is a way to change the crickets noise. You need to change out the crickets.wave file to another .wav file and restart the PBX Service.
UPDATE: Make sure you rename your new .wav file to "crickets.wav" The UC server only looks for that name
1. Copy the current crickets.wav file to a different location for backup purposes.
2. Copy the new .wav file to the conference folder
3. Rename the new .wav file to crickets.wav.
4. Restart the PBX Service.
5. Call in and test the conference server.
The crickets.wav file is located here:
ADTRAN\NetVanta UC Server\SIPPBX\prompts\system\CONFERENCE\crickets.wav
Let me know if you have any problems.