Tag: sip

SIP Dialog

VoIP security architecture in brief

Voice over IP (VoIP) has been around for a long time. It’s ubiquitous in homes, data centers and carrier networks. Despite this ubiquity, security is rarely a priority. With the combination of a handful of important standard protocols, it is possible to make untappable end to end encryption for an established VoIP call. TLS is the security protocol between the…

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Jitsi, ostel.co and ISP censorship

Earlier last week n8fr8 suspected something changed on the ostel.co server, due to many users emailing support specifically about Jitsi connectivity to ostel.co. The common question was “why did it work a few weeks ago and now it doesn’t anymore?” The tl;dr follows, skip to keyword CONCLUSION to hear only the punch line. To support n8fr8’s hypothesis, there was a…

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Build your own Open Secure Telephony Network, some assembly required

The Open Secure Telephony Network is a standard that defines how to configure a VoIP softswitch with the capability to have secure two-way VoIP conversations if both parties are using the same server. The system requires both backend and frontend components, which makes OSTN is a little different than some of the other Guardian apps. Unlike Gibberbot, there are few…

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Cross-Domain calling, or “toll-free long distance VoIP”

In a standard OSTN configuration, the Fully Qualified Domain Name (FQDN) of the server running Freeswitch is a core dependency to operate the service. For example, the domain ostel.me was first configured as a DNS record, a server was bootstrapped with ostel.me as the local hostname and a Freeswitch cookbook was run using the Chef automation system. Because the domain…

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