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Security for VoIP

Encryption, Authentication, and Firewalls

While the topic of security was of minor significance in traditional telephony, it can no longer be neglected during the integration into the IP world without becoming guilty of gross negligence. Anyone who intends to protect their VoIP installations should be familiar both with the impending threats and the counter-measures. The course systematically analyzes points of attack of VoIP and explains the available protective measures on the network and application layer. The latter are then weighted on the basis of the different VoIP architectures. The students learn how to provide adequate VoIP security in their own future projects.

Course Contents

  • Principle Dangers for VoIP
  • Attack on the Media Stream
  • Attacks on Signaling
  • Attacks on the Devices
  • Security Measures in the LAN and WLAN
  • Port Security and Authentication According to 802.1X
  • Security Measures in the WAN
  • Identity under VoIP (SIP Identity)
  • Local Authentication and via Proxy Chains
  • Problems with Certificates
  • SIPS and S/MIME
  • SRTP and SRTCP
  • Key Management with SDES, ZRTP, DTLS, and MIKEY
  • WebRTC
  • VoIP and IPSec
  • NAT Solutions: STUN, TURN, and ICE
  • Firewalls and VoIP
  • Session Border Controller
  • SIP-Connect 1.1


In this course of the ExperTeach Networking series, each student will receive the comprehensive ExperTeach course documentation.

 Detailed table of contents

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Target Group

This course addresses designers and technicians responsible for the design and implementation of VoIP installations.

Knowledge Prerequisites

Profound know-how of the TCP/IP protocol family and common LAN technologies is required. Students should be familiar with security concepts, such as encryption and authentication. These can be imparted, for instance, in the Security in IP Networks—Identifying and Closing Security Gaps course. Sound basic knowledge about VoIP is another prerequisite.

Course Objective