Asterisk + DAHDI + TDM840 = No FSK MWI?

Using Asterisk + DAHDI, the FXS lines on my TDM840B get their FSK VMWI spill as expected. Testing *, same DAHDI, results in no FSK spill, only a line polarity reversal.

Stutter dialtone is correctly generated in both cases.

Is anybody running a similar setup with FSK MWI devices? Does it work for you?