S.D. Codified Laws § 49-30-22
The capital stock of any corporation organized under this chapter may be increased to such amount as may by its stockholders be deemed necessary for the construction or operation of its lines of telegraph or telephone, by a vote of the owners of at least two-thirds of all its stock, in person or by proxy, at any annual meeting, or at any meeting called by its directors for that purpose by a notice in writing to each stockholder, to be served on him personally or by depositing the same in the post office, postage paid, properly directed to him at the post office, if known, nearest his usual place of residence, at least twenty days prior to such meeting. Such notice shall state the time and place of such meeting, its object, and the amount to which it is proposed to increase such capital stock. No vote in favor of such increase shall take effect until the proceedings of such meeting, showing the names of the stockholders voting therefor and the amount of stock owned by each, shall be entered upon the records of such corporation.
SDCL 49-30-22