Yes, this substitution system needs to be revised. It should be obvious that invitation sound should be received if a substituter is wanted. Currently, the substituter doesn't hear any sound (Many of us are doing other stuff in computer and BBO website is minimized!). By the way, if you see Account --> Settings --> Sound: invitation (activate/not activate), then sound is received if you enlist your name on a tournament's Partnership Desk, and get invited
For me, the most exciting is to play with a woman partner; in tennis they call it mixed doubles. Any intermediate or better female player, who also knows a bit more about standard conventions (eg Bergen raises, Jordan 2NT, Lebensohl, Drury, MSS etc)? My user name in BBO: oldboy_EST