This is a highly informative comment from the amsn source: 

#TODO:when we write a message to a CW, it should do the same as WLM, 
#try to open an SB, if the CAL answer is 207
Come on people, is it so hard write 'chat window'?

There is also the most awesome error message I have ever seen. Admittedly, we can't blame this one on the amsn people as it's part of the MSN protocol. 

713 {
        status_log "CALReceived: 713 USER TOO ACTIVE\n" white
        return 0
}
Bad user!