DTMF issue

Well, Asterisk Mail refuses to recognize my DTMF tones from my remote extensions behind NAT.

It’s weird because all of my IVRs accept the DTMF input from remote extensions. Also, if I call a number outside of my PBX, the tones are recognized. It’s ONLY when dialing voicemail, and ONLY from those remote extensions.

One more quirk. The tones are recognized if I dial from that remote extension to another extension, wait for the voicemail prompt, then login. ???

So I guess it’s only when using *98 or *97 to access the voicemail.

Where should I start?