The Public Utility Commission has power to require any telecommunications utility, after a public hearing of all parties interested, to extend its line, plant or system into, and to render service to, a locality not already served when the existing public convenience and necessity requires such extension and service. However, no such extension of service shall be required until the telecommunications utility has been granted such reasonable franchises as may be necessary for the extension of service and unless the conditions are such as to reasonably justify the necessary investment by the telecommunications utility in extending its line, plant or system into such locality and furnishing such service. [1987 c.447 § 4]