MWI with Audio codes (behind a NAT) for stutter tones

Looking to find out if any has Audiocodes gateway that supplies stutter tones to indicate Voicemail waiting.

I have these units working, but most are facing a key-PBX and dont require the VM.
But this one is a POTS replacement and does require VM. It also happens to be behind router.

Which audicodes? I know it works on an mp-114 and I don’t remember having to do anything funky.

I have the unit behind a D-Link broadband router, I know this sounds lame, but I just saw that the unit didn’t have the port forwarding for 5060, is that required?