The flash call feature is often unreliable on this phone... it usually ends up dropping the call from the original caller if the caller trying to be reached is unavailable, so I have been forced to dial from a second line and then conference the calls. My dilemma is this... what if I have a caller on line 1 who I've put on hold, then a call comes in on line 2, then I need to use line 3 to dial out and conference those calls - is that possible? And if so, would I be able to return to line 1?