[USR-TC] Question about Quad Modems D/A and outdials...

Hello, We're using a TC1000 chassis with some Quad Modem digital/analog v.90 cards as modems (via RS-232 card) dialing out over PRI for a legacy outdial application which dials out to a variety of ISDN and POTS modems. We seem to be having some strange issues when dialing some of the old Motorola Codex 33.6K modems. Does anyone have any experience in this area, or have you seen any compatibility issues between these modems (or others)? Thanks in advance for any assistance or advice you might be able to offer. Thanks, Todd