gistfile1.txt

class Phone
  has_many :line_assignments
  has_many :lines, through: :line_assignments

class Line
  has_many :line_assigments
  has_many :phones, through: :line_assignments

class LineAssignment
  belongs_to :phone
  belongs_to :line

  line_pos:integer


ph.line_assignments.where(line_pos: 1)
line.phones
ph.lines