Standard Practice for Voice over Cat5

Hi – When running voice over Cat5, should you typically run 1 phone line per Cat5, or multiple lines per cable?

If one line per cable, what is the proper thing to do with the un-used pairs on the telephone block in the closet?

If multiple lines per cable, what is the best way to break out the lines on teh users side to connect to telephones in a neat way?

Thanks –