This paper describes the usage of OPNET simulation tool to evaluate VoIP over MPLS networks which employs RSVP protocol as QoS mechanism with SIP or H.323 as signaling protocols for setting up VoIP calls over the Internet. The results showed that the H.323 with RSVP over MPLS networks produced minimal end-to-end delay than SIP protocol; making it a good choice as a signaling protocol with VoIP over MPLS networks for places requiring minimal end-to-end delay, while SIP reported lowest delay jitter with minimal call setup time
Azeddien M. Sllame, Asra Hema, Huda Alnajem(3-2018)

Multi Protocol Label Switching (MPLS) is a core networking technology that operates essentially in between Layers 2 and 3 of the OSI model; for this reason, MPLS has been referred to as operating at Layer 2.5. MPLS can overlay existing technologies such as Asynchronous Transfer Mode (ATM) or Frame Relay, or it can operate in an entirely IP native environment; this can allow users to take advantage of existing Customer Premises Equipment (CPE) while making a move towards converging all network traffic, such as data, video and voice, at a pace that users can accommodate and afford. MPLS provides. its users a number of advantageous features such as traffic engineering, network convergence, failure protection, and the ability to guarantee Quality of Service (QoS) over IP. arabic 2 English 27
Mariam Abojela Msaad, Amer R. Zerek , Wesam M. Tohamei(1-2012)

in wireless networks, mobility is an important issue because Internet connectivity can only be effective if it is available during the movement of a node. To enhance mobility, the IEEE802.16e standard has set procedures to design wireless access systems to operate on the move without any disruption of services. The major difference between mobile WiMAX and fixed WiMAX is mobility support. However, speed and trajectory of nodes are unpredictable and can vary even in identical circumstances. In this paper mobile node trajectory is studied under different codecs schemes in order to evaluate the effect of node movement, towards or away from the base-station, on end to end delay, jitter, mean opinion score and throughput of a VoIP application. The results showed that trajectory inward improves network performance since mobile node gets closer to the base-station and hence signal is improved and less power is required. arabic 12 English 67
I. Almerhag, N. Aboalgasem(5-2017)