All Services Programming & Development Telephone Systems $5/hr · Starting at $25 I've worked in telephony since 1997, developing IVR systems, protocol converters, telemetry systems, built and sold a small UK telco and an IP Centrex company.Skilled in TDM and IP, Asterisk, FreeSWITCH, OpenSIPS, etc. About $5/hr · Ongoing Download Resume I've worked in telephony since 1997, developing IVR systems, protocol converters, telemetry systems, built and sold a small UK telco and an IP Centrex company.Skilled in TDM and IP, Asterisk, FreeSWITCH, OpenSIPS, etc. 0 Reviews This Freelancer has not received any feedback.