In 1954, Huldah and her late husband, Rev. Dr. Mark Buntain, agreed to travel to India and serve in Calcutta for one year.  That year turned into a lifetime of service to the people of Calcutta and its surrounding states.  Together, they established a holistic inner-city and outreach ministries consisting of more that 100 schools with 22,000 children including a blind school, 950 churches, 5 bible schools, daily street and school feeding programs for 25,000, a nursing school and a full general Mercy Hospital that has treated 2.2 million people and provided free care to 880,000 patients.

After her husband passed away in June 1989, Huldah became Chairman and Senior Pastor of the Calcutta Mission for a number of years.  It was a fulfillment to the late Pastor Mark and Huldah's vision in the recent selection of Calcutta's national leadership.  At that time Huldah became President of Calcutta Mission.

Sincce her husband's death, she has continued to faithfully serve the people of India, and also travels extensively around the world raising funds for projects in all of the vast areas that come under the Calcutta Ministries.  In 2006, Huldah founded Calcutta Mercy Ministries to support the comprehensive ministries that she and her late husband built over the past 57 years.