Callam was born in Jamaica to a committed Baptist family, his father a deacon and his mother involved in other ministries.
He is a popular speaker at forums, symposiums, seminars and workshops throughout the world.
He created and ran The Breath of Change (TBC FM), a religious radio station, and was a founding director of the National Religious Media Company of Jamaica, the operator of LOVE FM and LOVE TV.
He has also served as Chairman of the Board of the Public Broadcasting Corporation of Jamaica.
He has been vice president of the Caribbean Baptist Fellowship and from 2000 until 2005 he was vice president of the Baptist World Alliance, having served on many of its committees, commissions, and workgroups, including the general council and executive committee.