I work on IT more than 12 years. VOIP/Asterisk Developer, Expert System Administrator and Network Administrator, Perl Programmer.
Generally, I develop solutions based on Asterisk and speech technologies (speech synthesis and speech recognition systems), complex IVRs, integration with external sources and databases, custom click-to-call and callback systems, etc.
I prefer custom development for Asterisk and FreeSWITCH. Usually, I use Perl for development.
I have huge experience in solutions based on Asterisk such as FreePBX, Elastix