i have an asterisk/trixbox server. I have 3 analog lines connected to a 3 fxo card. What i need is a way to have a main number for my office. This number when dialed should rarely be busy. What i am thinking perhaps can work is this. A user calls line/zap 1 (Main Number) and the asterisk server sends the call to line/zap 3 releasing line 1 for another call. Another call comes in if line/zap3 is still busy then it send the call to line/zap2. And if both backup lines are busy then line/zap1 handles the call. Can this work? Is this the best option for the reasources in place?