I think the "DCOM doesn't work over dial-up" came about from the practical speed limit of analog modems, not a technology limitation.
As far as ISDN, as long as your TA dials your ISP on demand, you should be OK as long as the delay for dropping an unused connection is long enough so that it stays up while waiting for server components to respond.
i.e.:
- Client makes request
- TA dials ISP and forwards request
- TA times out due to perceived inactivity and drops line
- Server responds, only to find no connection to client any more.
So, set the delay long enough that your connection doesn't drop in the middle of a conversation.
Chip H.