Hay_wire, that may be a complicated request to fulfill. We had a similar request some time ago, except instead of phone calls they wanted emails to do the same trick: IF <thisguy@work.net> emails <myname@work.net> THEN set alert volume to 5 and play sound Droid AND THEN set alert volume to 0.
It is a pretty complicated thing to do, believe it or not, because Impel doesn't know when the sound event has started or stopped, at least not using the Android APIs that we currently use. I will ask the engineers again to see what they think, but I would say that this request may be quite a ways off from showing up in a release.