I get a complaint often that when users start to dial, the phone dials that initial digits (area code, etc) and says "extension not found" or some similar problem. There are probably timers at play with that? (and does that affect 911 call timing?) ... but users would like to be able to dial the full 10 digits before the call takes off. I tell them to dial and THEN lift the handset but it is intuitive to do it the other way around with traditional telephones, so it is a hard habit to break. Just a thought for improvement.