Editor note: see the updated version of this post here.
As described in previous posts, WebRTC does not specify a particular signalling model other than the generic need to exchange Session Description Protocol (SDP) media descriptions in the offer/answer fashion.
During the last few months, my friend Antón Román (CTO of Quobis) and I spent a lot of time with our team figuring out how to manipulate and adapt the SDP’s generated by web browsers to make them compatible with the different server/gateway technologies we’re working with.
As WebRTC makes use of new mechanisms but also existing ones that have seen few deployment in real networks to date. SDP’s generated by Web Browsers are more complex and contain a number of new attributes that are unfamiliar in SIP or IMS networks. In the following post, Antón analyses the anatomy of a WebRTC SDP, giving a detailed description of what all those lines do.