In the first part of this paper the reader is introduced to the concept of transmission of audio traffic over the Internet in order to gain a theoretical background for the understanding of presented experiments. In the practical part of this paper the influence of network elements on transmission of multimedia content is shown through various scenarios in wireless local networks. The goal of each scenario is to describe the behaviour of network elements and their influence on network attributes through specificly designed situations. The first scenario shows what influence the roaming between two access points of the same network has on call quality for the mobile user. The next scenario continues on the first experiment and it shows how the RTP protocol calculates network attributes based on variables in packet headers from that first experiment. The measurements of network traffic were done in the third scenario on the same path with different codecs in order to make a comparison of their performanse. There were multiple roamings between access points during the call on the common path and the behaviour of codecs is concluded for those network conditions. The behavior of video call on the path from previous scenario is discussed in the forth scenario, and the audio and video flows are compared. Same measurements as in the third scenario are made in the last scenario with the exception of network congestion in one part of the network, from which is the comparison of codec performanse in stable and unstable network conditions obtained.