Hi Paulgent,
Voicemails are just wav files saved in individual folders, one folder for each extension. Accompanying the voicemail is a companion XML file (same name different extension). In the XML file there is a property for "HEARD" and a date and time --IF-- the voicemail has been heard. The brute force approach would be to check this property in each XML file. If the HEARD property is missing, you know the voicemail has not been heard yet.
We handle your challenge with our our Voicemail Manager tool. This tool allows managers to log into the web interface and see a list of voicemails for all the users this person manages. Like our Recording Manager tool, this tool allows you to listen to the voicemails, download, forward, or email the voicemails. But perhaps more to your specific need, it can monitor voicemails that have gone unheard for a specified period of time and forward that voicemail automatically to the manager. Different groups can have different expiration schedules. For example maybe "Sales" doesn't want voicemails to go unheard more than an hour, but "Support" doesn't want to escalate for two hours.
Since we are on the subject of Voicemail Manager, I should also point out that we can compress, archive, and forward voicemails as MP3 files (important for some email clients), and we have an enhanced Group voicemail feature that allows you to have a custom intro prompt, and it actually propagates the actual voicemail (turns on MWI light) to each user rather than just sending an email.
