The 'H' simply tells the Voicemail to transfer to that phone, and immediately hang up ... a 'blind' transfer.
This allows the phones to be programmed to control the call forwarding, rather than tie up a VM port.
The #604 as given in that thread:
Try Intercom, #604,desired extension, Speed Dial, XX, Redial.
XX = number of seconds of ringing before forwarding.
is perfectly correct. The 'XX' is optional, if you don't enter it - it defaults to 8 secords, as I recall. Make sure you're forwarding to the main pilot number of the Voicemail.
#601 doesn't allow you to set ring time because that is the code to forward all calls... if you're *always* forwarding, there wouldn't be any need for any time delays.
I've never seen anything programmed for XXXV... that's a new one for me. There's no 'V' token... there's a '%V' token that is a replacement for what's in the 'variable' field.
But what I think you're talking about is what the LCD says in the phone... I can't recall, but I think that just means the [V]oicemail.
After programming the call forwarding on the phone, you also have to program the following:
#656 91 Ext (redial?)
#657 92 Ext (redial?)
The 656 sends the mailbox number - so that when you call forward to the voicemail, you go to the correct mailbox.
The 657 sets your message light to go to the correct mailbox.
You might be hearing the "invalid entry" because your 656 is set to an invalid mailbox number.
The 91 & 92 codes are for Toshiba voicemails, if you're using a different manufacturer's VM, then I couldn't help you.