Re: [Linphone-users] Truncated response to SIP Options message

[Klaus Darilion]

Hi Keith!

Those 4 bytes are probably CRLFCRLF and are used as light-weight keep-alive.

Actually CRLF keep alive over UDP is not standardized, but it is a 
defacto-standard implemented by many client and supported by almost any 
server software.

regards
Klaus

Am 20.05.2010 16:50, schrieb Keith Jacobs:
> Whilst sniffing the traffic between several hundred Linphone endpoints
> and an Asterisk server I see that whenever the Asterisk sends out a 'SIP
> Options' message to any client, the client first responds with an
> invalid SIP message (to port 5060 but only 4 bytes of data) followed by
> a correct response some 10ms later. Does anyone know what this is all
> about? Can it be stopped?
>
> Thanks
> Keith
>
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