Section 15F. (a) As used in sections 15F and 15G, ”bond” shall include a note or debenture.

(b) An entity that may invest pursuant to section 15A or the legal list may invest in the bonds of any company which at the time of the investment is incorporated under the laws of the United States or any state and may engage and is engaging in the business of furnishing telephone service in the United States, subject to the following: (i) the bonds shall be part of an original issue of not less than $25,000,000 in principal amount when the company is not incorporated in the commonwealth; and (ii) not more than 20 per cent of the assets of the entity shall be invested in the bonds of telephone companies.