The main problem we had with the *76 EFK toggle method was that it seemed to often fall down under multiple line registrations. The script we wrote would dial the *76 and toggle the phone's DND status indicator locally. The server-side toggle would only set the server-side DND status on the primary line, which for BLF purposes was OK. But often what would happen, though, was that the *76 would dial out on the second line registration if a call was ringing or in progress on the primary line. DND would be set on the secondary line/extension, and the local DND status would be toggled, but the primary line would still be open and not showing DND. So it put the local phone DND status to the opposite of what the server side and BLF hints were indicating. The only way to fix it was to turn toggle it so local DND was showing as disabled, and then hard-dial the feature codes to turn off DND for both lines to ensure things were in sync again.
I suppose on phones with only one line registration, this may be less of a problem. It's enough of a problem for our setup, though, that we're holding off on upgrading to version 4. The word from Polycom is that the one hosted IP customer they implemented this for isn't planning on upgrading to version 4 anytime soon either.
