Mediation server tasks
The Mediation server performs the following operations:
Identifying the type of network that a voice call will use
Selecting the best codec for the aforementioned network
Converting signals and media according to the previous points, such as translating SIP over TCP to SIP over TLS, translating media (G.711) on the gateway to RTAudio on CS, or for media traversal of NAT
Note
The most used codecs are: G711 (better quality but requires a network without packet loss) or RTAudio that is also able to work with a certain number of lost packets (RTAudio has a native error concealment module).
Talking about codecs, we should take a look at the document Network Bandwidth Requirements for Media Traffic (http://technet.microsoft.com/en-us/library/jj688118(v=ocs.15).aspx) that is really important for planning and understanding the bandwidth requirements for every single solution. If we are preparing a project we could also use the Lync 2010 and 2013 Bandwidth Calculator article at http...
