Fred Posner

Kamailio Consultant, VoIP Engineer, SIP Expert

Fred Posner (qxork)

Fred Posner profile photo

Fred's primary role is a VoIP Consultant, specializing in Open Source software including Asterisk, Kamailio (formerly OpenSER), and FreeSWITCH.

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Kamailio / SIP Expert

For more than 20 years, Fred Posner has provided VoIP consulting services; specializing in open source communication products such as Kamailio, Asterisk, and FreeSWITCH. Clients utilize Fred's services for design, implementation, and support (including emergency support).

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Have SIP / Will Travel

2019 SimCon Award Pre-Posthumous Legend

Fred enjoys evangelizing open source telecom and has spoken at Kamailio World, Astricon, ITEXPO, Cluecon, Asterisk World, and more.

Fred loves the open source VoIP community and was honored to receive a 2019 SimCon Award recognizing his support and contributions.

» About Fred

Open Source VoIP Consultant

Fred provides SIP/VoIP Engineer consultation services including architecture, design, support, and more.



Kamailio expert, speaker, and consultant. Proudly working with Kamailio/OpenSER since 2005.

Kamailio (formerly OpenSER) is an Open Source SIP Server released under GPL, able to handle thousands of call setups per second.

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Asterisk powers IP PBX systems, VoIP gateways, conference servers and other custom solutions. It is used by small businesses, large businesses, call centers, carriers and government agencies, worldwide. Learn More about Asterisk »

» Learn More about Asterisk Consulting



FreeSWITCH is a scalable open source cross-platform telephony platform designed to route and interconnect popular communication protocols using audio, video, text or any other form of media.

» Learn More about FreeSWITCH consulting

Open Source Software Myths

Presentation from Kamailio World 2018 in which Fred discusses common myths regarding Open Source software.


In 2020, Fred launched APIBAN as a free service to help protect SIP servers from unwanted SIP traffic.

APIBAN helps prevent unwanted SIP traffic by identifying addresses of known bad actors before they attack your system. Bad actors are collected through globally deployed honeypots and curated by LOD/APIBAN.


Fred utterly embodies the definition of 'reliability' and 'quality'.

Dean Wells, Principal Program Manager

Fred should be your go to guy.

Michael White, Principal @ .e4

A tireless and enthusiastic advocate on behalf of the Kamailio project and, more broadly, in the service of the open-source VoIP ecosystem.

Alex Balashov, SIP Expert

Fred has a very strong work ethic and is a great problem solver.

Andy Day, VP Carrier Services

Fred's problem solving skills have a razor precision that borders on freakish.

Patrick Goldberg, Chief Solutions Officer