Hi,
I had the same problem, but found a workaround to record the messages with the record-file function. Which means: don't use this "leave-msg-for xxx" but "record wave file" in the OGM settings.
There you can exactly define, how long the recoding should be, etc.
In the filename you can insert variables, so that each recording produces a different file name.
Works fine, the only problem is, that you need to set up your own menu for listening your messages.
(which I'll do anyway, because I don't like this built-in menu...)
regards

Tjareson