I need to make sure that none of the lines coming into my PBX are allowing access over a modem for management. I have found a few that give me the modem squall (I manually dialed every single DID). How can I tell if the line is used for a fax vs embedded modem for management or whatever in the PBX?

By management, I mean eManager, but don't know if there is any other management protocols that might exist.

List all your DIDs by going to DID Table view. If the DID goes to the PBX internal modem, then it tells you in the table. You can also export this to CSV. Be aware that the previous installer could also have a way through the voicemail system by setting up a transfer mailbox. I don't know what type of voicemail system you have. For Toshiba voicemail, it could be an IVP8, Stratagy ES, or a MAS.

Also, look for DISA in the table view. Unless users specifically need DISA access, I would remove it.

We did have an outside line that went to the DID for built-in modem. For now I redirect that on the gateway that sits between this PBX and the provider...I redirect it to my IP PBX and terminate the call. DISA appears to be disabled on trunk, so I guess I don't have to worry about that.

We have the IVP8 VM cards, how can I look for the transfer to the modem? How about authentication, how is that handled for that modem connection?

I'll send a private message about the transfer mailbox, but what I would do first is change the security code for mailbox 999. I would typically be more concerned about hackers than the previous installer.