Hi Daniel,
Here is some feedback based on my 5 min TOC overview:
1. Although the book refers to a particular version of kamailio but as we know from 4.0.3, sercmd has been replaced by kamcmd and this could potentially become a cause for confusion for some readers since the chapter titled Kamailio tools has the following section which constantly refers to sercmd.
2. If I was the author of the book, I would definitely add a bit about webrtc and websockets. At least I would like to see these two words in the TOC and perhaps one or two page description of what kamailio 's websockets module could do and if you have any future work planned.
3. ser/kamailio has a distinct role to play in the IMS test beds that I have seen in labs. of various telecom vendors but the book TOC apparently makes no reference to Kamailio's IMS capabilities. I think now there are a lot more IMS modules as compared to few years back when there was only ser based openimscore. It would be a bit unfair to miss this key contribution.
Cheers,
Adnan