Spurious "missed call" message

Our system (Asterisk 1.2, SPA 942s) is set up to ring each handset on an incoming call. Whoever is available picks up the call. This is great, except that all of the other handsets subsequently show “missed call”; when you come into the office, you don’t know which calls were actually missed, and which were just picked up by someone else.

Does anyone know a command that Asterisk can send to the phones so that they will not show “missed call” if another extension picked up the phone?

Much thanks!

Does the phone manual specifically indicate such capabililties? I doubt if any non-proprietary system can do this. On the other hand, if the phone has an input for this, there might be a way to do this in Asterisk.