Here is a simple script, written in perl, that creates a file of custom auto-attendant prompts, suitable for uploading to your OBi. I'm running it on Windows under ActiveState's free perl. It does nothing exotic, so I'd expect it to work ok on a Mac or Linux system as well, using the perl that comes preinstalled. Let me know of your success or failure on other platforms.
The script looks in the current directory for files named user1.wav, user2.wav ... user10.wav and uses those found to create a combined file, useraa.dat that can be uploaded to the OBi. Each input file must be mono, 8kHz sampling rate, G.726-32 encoded, with length between 0.25 and 60 seconds.
Various tools I tried, including Audacity, an old copy of Audition, and several converters, would not produce a G.726-32 file of good quality. One solution is to to create the prompts in your favorite authoring tool, save as 16-bit PCM wav format, then convert with ffmpeg, which is free and readily available for Windows, Mac and Linux. The command is e.g.
ffmpeg -i original.wav -acodec g726 -ab 32000 user1.wav
Once you have all the user<n>.wav files, run the perl script and upload the useraa.dat to your OBi.
I'd appreciate feedback on any quality issues, better ways to create G.726-32 files, etc.
Before uploading, make backups of your config and current prompts. While developing this code, I had a bug that caused the OBi to endlessly reboot. I believe that is now very unlikely, but if it should happen to you, don't panic and see this thread: http://www.obitalk.com/forum/index.php?topic=1726.0
Just in case you don't have a backup, a copy of an empty prompts file, courtesy of Obihai support, is also attached.
This is open source free software and I'm imposing no restrictions on its use. However, if you fix bugs or add features, please post the improved code here. If you incorporate it in a larger project, please provide an acknowledgement.