This book is primarily targeted toward candidates of the CVoice exam. However, because CVoice is one of Cisco's foundational VoIP courses, this book also serves as a VoIP primer to noncertification readers.
Many Cisco resellers actively encourage their employees to attain Cisco certifications and attract new employees already possessing Cisco certifications, for higher discounts when purchasing Cisco products. Additionally, having attained a certification communicates to your employer or customer that you are serious about your craft and have not simply "hung out a shingle" declaring yourself knowledgeable about VoIP. Rather, you have proven your competency through a rigorous series of exams.