Definity G3si with Asterisk VM only

Hello-
Does anyone know if it is possible to replace an Audix Voice Mail server with an Asterisk Voice Mail server? Our g3si switch currently has 6 analog lines that go into the audix vm server. I have seen guides talking about Asterisk pbx integration with definity g3si through the use of t1/e1 trunks. I do not have any spare t1/e1 trunk cards in the definity.

If analog lines are possible would I need FXO type ports on the Asterisk or FXS ports or a combination of both(I would need auto attendants that could forward a caller back to an extension on the definity pbx)? Also, would the MWI function still work with Asterisk? Thanks for any help.