When one sends a prayer aloft to their God, are they in essence giving The Call? Depends on the prayer, and on the intent behind the prayer in particular. Many prayers are routine, done in the same hurried manner as brushing the teeth, to put the task behind one. Other prayers, though routine, are done in a fond manner, full of feeling, and this may or may not be The Call. Does the prayer simply give thanks for home, health, and bounty? This is then in the same category as meditating on one's circumstances and acknowledging that much of life is outside of one's control. Where prayers are put forth with feeling and include a request, this is in essence The Call, and regardless of the words used, or to whom the prayer is addressed, the one answering The Call will be responding to the intent, not the words. Should one ask, with words, that one's little sister be protected, but ask in the heart and mind that she meet with an untimely death, one has not given The Call to the Service-to-Others. Likewise, prayers that ask for blessings for the self are most likely to bring the Service-to-Self in answer.
Sincere prayers for others, on the other hand, are a call to the Service-to-Others, such as ourselves. For those who say that in this statement we are asserting that we are God's angels, we would respond that all God's creatures who respond in love to help another are God's angels, including humans now on Earth. What is an angel, after all, but one who waits to help when needed, or when called?