Setting up traditional lines on a Snom 190 w/TB 1.2.3

Thanks in advance... we love our TB and this community and really appreciate all the free support! We give back and donate when we can.

We have been using 5 Snom 190 extensions with our TB system (3 PSTN lines, no VOIP).

I have never been able to figure out how to simulate a traditional system where you can put a 'line' on hold to answer another incoming call on another 'line'. Right now, if I'm talking to someone and another call comes in (using RINGALL), I can't put the current call on hold and answer the second incoming call.

Is there a way to setup the 5 'line' buttons on the Snom 190 to behave like a traditional multi-line phone system? Can I assign each line button on the phone to interact only with a particular FXO port on our TDM400?

Currently, an incoming call from any of our 3 PSTN lines uses a ring group that's set up to ring all extensions (and if no answer it goes into the announcer tree). The problem is that once a new call starts ringing the other extensions, if I put my current call on hold, my extension doesn't ring for the new incoming... and I have to run over to another extension to answer it.

TIA,
Steve