Today, the Voice over Internet Protocol (VoIP) is a very growing service because of the increasing utilization of IP networks in modern enterprises. Its major benefit is the reduction of the operational and infrastructural cost that is vital for disaster management planning. This paper presents a literature review on voice transmission techniques over IP networks and discusses the advantages of the Multi-Protocol Label Switching (MPLS) backbone for transmitting voice packets. This could be a case of an emergent communication case where there is a need for utilizing available infrastructure along with the VoIP protocol. We focus on the identification of the constraints that affects the quality of service provisioning to the end users and we suggest a set of modifications to improve it. Further, we propose a plan to develop a script format to achieve optimization of voice packet (real-time) transmission performance over a MPLS based network.