I think I am on the same boat like many others: My family has a land line from my local telephony company and we have two cell phones (lines) as well. We live in a two-story home.
I am considering unifying three phone numbers by using Asterisk. I want a PBX such that:
1) It supports multiple extensions so that I can make internal/intercom call or transfer call to another extension easily
2) The two cell phone lines can be converted to land line alike service and I can connect them to FXO ports. So I will have three, instead of one incoming line.
3) When a person calls me, depending on which number he is calling, there are different ringtones. But I can always use any handset to answer the call.
4) The land line will be the default phone line when I place an outbound call. If the land line is busy, I can choose to use cell phone number #1 or cell phone number #2 to make a call. I do not want to use cell phone to make a call. Instead, I want to use regular VOIP phone handset to place a call.
Is it possible?