We have a fairly ancient Norstar StarTalk Flash phone system, 7 lines, 14 stations. We have one line that is dedicated to one department, it's like line 4, has a distinct ring on one station, and a normal ring on the other stations programmed to ring (common area phones.)

This line is supposed to roll over to the station's voice mailbox whenever someone calls and the phone is on the line; we've recently heard from people calling in that they are getting a busy signal, not voice mail.

I'm trying to look into this, I have all of the books for the phone system, but they are REALLY confusing if you are not the one that set up the system (I'm not, this thing predates my time here by several years ) since a lot of the instructions assume you are following along.

Where can I start looking, I'm sure that some setting got tripped somewhere along the line and needs to be re-set.

Any help would be muchly appreciated! Thanks!

Check the VM ext of the Startalk (F985)
Is the Foward busy of the station pointing to the VM DN?

Unless you have DID trunks the second call would have no way to get into your system. Are you sure this worked before? Maybe you had a voicemail box provided by your telco.

I checked and when I did the Feature 985, it said Set 51. 51, I'm fairly sure, is our voice mail system, as whenever someone is in the VM system leaving a message and I hit that line it shows 51 as the extension using that line.

I don't know about the trunk thing, I'm not sure what you mean by that.