Voicemail capable modem

To All,

I recently picked up an older Mac, 6300CD, and I would like to add
voicemail to it. Ebay always has voicemail software available and I do
have a need for it (combo simple voicemail & fax - network connected)
however, I have no modem in this unit and have no clue which modems that
will fit with this machine are capable of voicemail. Typically, the better
sellers give links to various programs that can check an existing modem,
but I don't have an existing modem.

I have done a search on Apple's Knowledgebase, but no luck so far.

Is there a site, or does anyone reading this group have a list that gives
info on voice capable modems for this unit.

Regards,

John C.