Ok, the imap storage for asterisk voicemail works like the proverbial charm.
I needed some work on the home dialplan and setup before I could test it,
but I was able to leave a message to the home mailbox, seeing it stored
in the voicemail imap box and retrieve and delete it using a telephone
connected to the ISDN port accessing the VoicemailMain
application. The access number for voicemail is now set to 0140-1233
to (sort of) stay in line with the Dutch numbering plan. There is no
customer-service at 0140-1200 planned...