Extension vacant typically means, as you mentioned, that the phone with the that extension number is unplugged. If you have a voicemail box # 510 in the voicemail system, the phone system does not know that 510 is a valid extension. There has to be a valid extension number to be able to dial it from another extension. The voicemail and PBX do not communicate at that level. They do not exchange mailbox and extension information between each other.

You mentioned this is a new customer. Is this an existing setup that you are trying to troubleshoot? Numbers in the 5XX range are usually phantom DNs. One thought (assuming this was working at one time) is that the phantoms were put on a phone that is now unplugged.

I am not sure of the purpose of the other mailboxes, perhaps so that some people may have multiple greetings? Either way, the only you would be able to send callers to the 5XX mailboxes is either:

1) Press Transfer, dial Voicemail pilot number, wait for voicemail to answer, dial 998 (or is it 8 on the Stratagy Flash?), Enter mailbox number 5XX, hangup.

2) create phantom DNs for each phone that needs a second mailbox number. This will require programing to setup. Also need to setup call forwarding and VMID codes for each Phantom.

Last thought, is the extension numbers different then the mailbox numbers for some other reason? If the users only need one mailbox, in the 5XX range, then just make sure the VMID code matches the mailbox, ie.. extension 10 has a VMID code of 510 and uses mailbox 510 only. Internally you would still dial 10, but when the call goes to voicemail it would go to VM box 510.

David
Tele Express Business Systems