Building Telephony Systems with Asterisk
Barrie Dempster is currently employed as a Senior Security Consultant for NGS  Software Ltd a world-renowned security consultancy well known for their focus  in enterprise-level application vulnerability research and database security.  He has a background in Infrastructure and Information Security in a number of  specialised environments such as financial services institutions,  telecommunications companies, call centres, and other organisations across  multiple continents. Barrie has experience in the integration of network infrastructure and  telecommunications systems requiring high calibre secure design, testing and  management. He has been involved in a variety of projects from the design and  implementation of Internet banking systems to large-scale conferencing and  telephony infrastructure, as well as penetration testing and other security  assessments of business critical infrastructure.