Whole Linux: kernel hacking, scripting, all all all services (18 years of experience)
Whole voip: Asterisk, OpesSIPS, Freeswitch, custom modules for freeswitch from the scratch. (14 years of experience)
Whole web-programming: backend (grails), frontend (JS, CSS)
High load projects in voip, web-services (9 years of experience)
Project management.