Snom 4S - Manual (Page 3)

snom technology AG • 3
Table of Contents
1 Overview ..........................................................5
1.1 Applications ...................................................................... 6
1.2 Features ........................................................................... 6
2 Architecture .....................................................9
2.1 The NAT Filter and SIP ........................................................ 9
2.2 NAT ............................................................................... 10
2.2.1 How does NAT work? .............................................................................................................................................. 11
2.2.2 Symmetrical RTP ............................................................................................................................................................ 11
2.2.3 Signalling SIP ....................................................................................................................................................................... 11
2.2.4 Media RTP ................................................................................................................................................................................... 12
2.2.5 Classification of User Agents .................................................................................................................... 12
2.2.6 Probing Media Paths ................................................................................................................................................. 13
2.2.7 The Role of the NAT Filter .............................................................................................................................. 13
2.2.8 Optimizing the Media Path for Symmetrical NAT .................................................. 14
2.3 SBC Behaviour ................................................................ 15
2.3.1 Registering ................................................................................................................................................................................ 15
2.3.3 RTP Relay .................................................................................................................................................................................... 16
2.4 Scaling and Redundancy ................................................... 18
2.5 Detecting the right NAT Filter ............................................ 19
2.6 Requirements on User Agents ............................................ 20
2.6.1 Non NAT-Aware User Agents ..................................................................................................................... 20
2.6.2 STUN/ICE-Aware User Agents ................................................................................................................ 20
2.7 Defining the Maximum Session Time .................................. 21
3 Installation .....................................................23
3.1 Windows ......................................................................... 23
3.2 Linux ............................................................................. 28
4 Configuration ..................................................31
4.1 Logging In ...................................................................... 31
4.2 Port Binding .................................................................... 31
4.3 System Settings .............................................................. 33
4.3.1 Logging ........................................................................................................................................................................................... 33
4.3.2 Preparing Recovery ................................................................................................................................................... 34
4.3.3 General Outound Proxy ...................................................................................................................................... 34