Section 28. If the petition is brought by such trustee, the court shall issue a notice as hereinafter provided. If brought by a person other than the trustee, a subpoena shall be served upon the trustee as in equity, and upon proof of the existence of such trust estate as aforesaid by answer of such trustee or otherwise, which answer shall be filed within one month after the return day of such subpoena and shall set forth a schedule or statement of such trust estate, the court shall issue a notice as hereinafter provided. The notice issued by the court shall recite the substance of the petition, and shall be addressed to such absentee and to all persons who claim an interest in said trust estate, and to all whom it may concern, and to all the persons and classes of persons named as respondents in the petition, citing them to appear at a time and place named and show cause why said estate should not be held and disposed of under sections twenty-six to thirty-nine, inclusive.