Hello Juha, By server I mean our OpenSer. In our config we have else if (method=="NOTIFY" | method=="PUBLISH") { sl_send_reply("501", "Not Implemented"); return; } My question is whether this is correct according to your experience. Should we check for the "Event: keep-alive" header and send a 200 Ok in that case? Should the answer make a difference to the user agent? Is there a draft that defines what the response should be for NOTIFY messages depending on the "Event:" header? Thank you George Disclaimer The information in this e-mail and any attachments is confidential. It is intended solely for the attention and use of the named addressee(s). If you are not the intended recipient, or person responsible for delivering this information to the intended recipient, please notify the sender immediately. Unless you are the intended recipient or his/her representative you are not authorized to, and must not, read, copy, distribute, use or retain this message or any part of it. E-mail transmission cannot be guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses.