[Serusers] question regarding sip protocol

Hi, I am new to the sip protocol. I have been doing packet traces to understand how the protocol works. I am using the ser sip proxy version 0.9.6. I notice that once my phone registers with a proxy I get a 200 ok. Every 20 seconds after that the client sends a packet to the proxy. It is an Request: OPTIONS packet. My proxy responds with a Status:404 Not found. I tried to do some research on this but could not find anything useful. Does this response of a 404 matter? How can you fix this? I have read that the client does this as an application level ping to make sure the proxy is up. If I have 100s of people registering that is a lot of extra traffic. Is there a way to stop this options query or have the proxy respond properly? Thanks Michael Network Services Engineer ________________________________ DISCLAIMER: This e-mail may contain information that is confidential, privileged or otherwise protected from disclosure. If you are not an intended recipient of this e-mail, do not duplicate or redistribute it by any means. Please delete it and any attachments and notify the sender that you have received it in error. Unintended recipients are prohibited from taking action on the basis of information in this e-mail.E-mail messages may contain computer viruses or other defects, may not be accurately replicated on other systems, or may be intercepted, deleted or interfered with without the knowledge of the sender or the intended recipient. If you are not comfortable with the risks associated with e-mail messages, you may decide not to use e-mail to communicate with IPC. IPC reserves the right, to the extent and under circumstances permitted by applicable law, to retain, monitor and intercept e-mail messages to and from its systems.