I would second this request. I have a small home office and I want calls from my office line to go out on my business line, and calls from the rest of the house to go out on my personal line
HOWEVER, it's extremely useful to be able to dial a prefix from the home extension to still dial out on the business line
At the moment I am not using AMP/Freepbx, and I modify extensions.conf to attach a prefix to the incoming call so that the caller id shows whether the call came in on the business line or personal line (and this is also used for distinctive ring detection. Then on the outbound I default to a particular trunk depending on callerid, but it can be overridden by prefix digits. Works very well, but not sure how to port this to freepbx?