Process Flex/Flash SPEEX Audio Data On The Server Side?

I'm implementing a very simple audio-only RTMP server.I have my client code like this:

// get the default mic
var mic:Microphone= Microphone.getMicrophone();
// best quality (picks up all sounds, no transmission interruptions)[code].....

Then on the server, I keep receiving audio packets with size of either 43 bytes or 11 bytes (no other sizes found yet).My questions are:

Why do I get size of either 43 bytes or 11 bytes (from SPEEX encoding?)?

Is the 43 bytes = 1 head byte + 42 data bytes?

What is the size of 11 bytes?

How should I process or convert the SPEEX to raw data, so that my server side app can use this audio data? My current implementation:

I pick up all 43-byte packets (drop all 11-byte packets);

Skip the first 1 byte;

Decode the left 42 bytes using Speex library.

How should I convert the raw data back to SPEEX audio data?