[USR-TC] Is there a way to get the modems to...

We are experiencing a problem with modems on Macintoshes. The Source-t folks with the help of 3COM (or whoever they are now) are telling us there are issues with Macs where they over optimisticly negotiate a connection speed then when the line can't support that rate the client drops. Is there a way to configure my HiperDSP's to be more conservative when negotiating a connection speed? Regards Doug P