To be honest, there is no intercept ( in uk version) so you would have to put it in to the disa first and then there is no incoming call groups so it could ring one extension at a time if you set up extension group. if you have a answering machine on the last extension it will pick it up. this is a basic unit.
The only way to use Disa is call comes in set AA for 1 for ext 101 ext call rings to that extension if you have smv card Fwd that extension to BV on no answer.

If the USA unit has somthing else to offer, one of the USA techs will let us know.

“I have not failed. I've just found 10,000 ways that won't work.”