Secure VoIP Protocols: So Long, Eavesdroppers!

Security protocols to the rescue!

The main reason for using a secure protocol for VoIP calls is because of the standard that almost every device uses to transmit audio and video packages between one another, Real-Time Protocol (RTP). Despite being so widespread, RTP is widely considered to be extremely vulnerable, as anyone with decent computer skills – or even dumb luck – can eavesdrop on communication between any parties. This is why equipping the RTP standard for VoIP with either TLS (Transport Layer Security) or SRTP (Secure Real-Time Transport Protocol) is a no-brainer for anyone that doesn’t want to have their calls and messages listened in on by third parties.

However, there are some major differences. TLS – and its predecessor, SSL (Secure Sockets Layer) – is a protocol capable of encrypting SIP signaling, thus making crucial parameters like phone numbers and user names invisible to snoopers. Additionally, TLS can also prevent the eavesdropping or capturing (and therefore block any tampering) of messages. SRTP, on the other hand, is a profile of RTP that, just like TLS provides encryption, message authentication and integrity, not to mention replay protection. In simpler words, SRTP encrypts audio and video media traffic, making it unintelligible for interceptors should they be able to capture messages despite any precautions you take.

How safe are VoIP calls?