VoIP & MS Teams

VoIP is a way of transferring audio and even video information all-across the Internet. But sending this type of real time data over the internet isn’t as simple as attaching a file to your email or sharing it via OneDrive etc… And all of this made possible via VoIP.

A VoIP call is made up of two parts

1.) Signaling: Signaling is the first part of the call. Every VoIP call start with Signaling. In case of MS Teams Signaling messages are based on HTTP Rest API. When user dials out a number, it will initiate HTTP Rest API signaling message. SIP is another widely used text-based signaling protocol. When a teams user dial PSTN number and it need to go via Direct-Routing/Operator connect, once call leave Teams phone system towards SBC, it will be SIP signaling protocol. Microsoft with Teams Direct Routing setup will receive SIP signal from SBC via TLS encryption. Other known signaling protocol are H.323 & Media gateway control protocol (MGCP).

2.) Media: Once signaling is responded and call is established then real time Audio and Video traffic will be taken care by RTP protocol. In case of MS teams it will be SRTP (Secured Real Time Protocol).