Section 39. The valuation at which the machinery, poles, wires and underground conduits and wires and pipes of all telephone companies shall be assessed by the assessors of the respective cities and towns where such property is subject to taxation shall be determined annually by the commissioner of revenue, subject to appeal to the appellate tax board, as hereinafter provided. On or before June 15 in each year, the commissioner of revenue shall determine and certify to the owner of such machinery, poles, wires and underground conduits and wires and pipes, and to the board of assessors of every city and town where such machinery, poles, wires and underground conduits and wires and pipes are subject to taxation, the valuation as of January 1 in such year of such machinery, poles, wires and underground conduits and wires and pipes in said city or town. Every owner and board of assessors to whom any such valuation shall have been so certified may, on or before the fifteenth day of July then next ensuing, appeal to the appellate tax board from such valuation. Every such appeal shall relate to the valuation of the machinery, poles, wires and underground conduits and wires and pipes of only 1 owner in 1 city or town, and shall name as appellees the commissioner of revenue and all persons, other than the appellant, to whom such valuation was required to be certified. Any appellee telephone company or board of assessors that has not filed its own appeal by July 15 may file an appeal by July 30 or 15 days after it receives notice of the original appeal against that appellee, whichever is later. In every such appeal, the appellant shall have the burden of proving that the value of the machinery, poles, wires and underground conduits, wires and pipes is substantially higher or substantially lower, as the case may be, than the valuation certified by the commissioner of revenue. The appellate tax board shall hear and decide the subject matter of each such appeal without priority over other appeals pending before it and give notice of its decision to the commissioner of revenue, the owner and the board of assessors; and except as provided in section thirteen of chapter fifty-eight A, such decision shall be final and conclusive. The appellate tax board shall consolidate for the purpose of the hearing and decision aforesaid all appeals relating to the valuation of the machinery, poles, wires and underground conduits, wires and pipes of the same owner in the same city or town, and in its discretion may so consolidate any or all appeals relating to the valuation of the machinery, poles, wires and underground conduits, wires and pipes of the same owner, although such appeals relate to more than one city or town. All appeals taken under this section by the same owner at the same time shall be deemed to constitute one appeal for the purpose of determining the entry fee payable therefor under section seven of chapter fifty-eight A.

The board of assessors shall assess the machinery, poles, wires and underground conduits, wires and pipes of all telephone and telegraph companies as certified and at the value determined by the commissioner of revenue under this section; provided, however, that in the event of a final decision by the appellate tax board or of the supreme judicial court under the preceding paragraph establishing a different valuation, the assessors shall grant an abatement, or assess and commit to the collector with their warrant for collection an additional tax, as the case may be, to conform with the valuation so established by such final decision. Assessment pursuant to this paragraph shall be deemed to be a full compliance with the oath of office of each assessor and a full performance of his official duty with relation to the assessment of such property, except as provided in the following section.