Paging on a Magix is only done through a loop start trunk port, so if you want to just unplug from the Magix and plug into the IP Office, you're going to have to use an ATM port. Your short code will be
*89 / Dial / {Blank} / {the unique outgoing line group for the ATM line}
Paging via an ATM trunk port will NOT allow simultaneous paging, through the telephone speakers at the same time as loudspeakers. If you only need Loudspeaker paging, it works fine.
If you want to interface paging through an analogue station port, programmed as a paging port, you must load the IP Office station port with a 600 Ω impedance, and isolate the IPO's battery voltage from the input of the paging equipment. This is done with a matching transformer, such as the Valcom VTM2 referenced above, or my go to, Viking Electronics AIB-1. This will give you a nice 600 Ω signal to the paging input of the amplifier. Bypass the TAM-B or UPAM, as they are not compatible with a dry loop paging signal.
If the amplifier doesn't mute music automatically via a VOX circuit on the paging input, and requires a contact closure during paging, add a Bogen UTI-1 paging interface to the mix. You still need the matching transformer, its output goes to the dry-loop paging port input on the UTI, with it set to VOX, so that when audio is present it will trigger a relay contact. This can then be wired to the Music Mute contacts on the amplifier, OR, the music source can be input into the UTI as well, and connect from the "Page & Music" terminals of the UTI to the paging input of the amplifier.
The advantage of using an analogue station port programmed as a paging port, you can include the paging port extension in a paging group and do simultaneous paging.