Debugging speechd-el network communication

[Lubos Pintes]

Hello list,
I am trying to implement the SSIP protocol on Windows. My goal is to use 
Emacs with speechd-el with SAPI voices.
To start with something, I implemented a very simple loop, which only 
sends the "200 OK" reply for every command it receives. Of course it 
interprets commands like "SPEAK", "SOUND_ICON", "CHAR", but currently no 
message priorities. I just want something which partially works, and 
them I will try to make it better.
I am using Emacs 24.3.1, speechd-el is latest and greatest from git 
repository.
Firstly I customized speechd-el to communicate over internet socket.
But when I run my server, I hear a message like "flet is obsolete 
blabla", and then emacs ceases to respond.
 From my program's point of view, the server is blocked on line where it 
wants to read the next command from speechd-el. It looks like Emacs is 
in some infinite loop, or frozen, it uses some CPU, but is 
uninterruptible. No C-G, no C-C, no Ctrl+Break works. I can only kill it.

Because I am very new to Emacs Lisp, to study the code is quite 
difficult. I would like to know where could I debug it to see what is 
happening.
Yet one last thing, I somehow, probably "by accident" pressed C-u and 
then M-x speechd-speak RET.
In this situation it worked better, at least it communicated with the 
server.
Thank for help