I had subscribed to your wonderful web page iptel.org, which truly is amazing in terms of SIP. 

However, please allow me to let you know that in all the SIP documentation you had provided on this webpage, none of the pages display the DIAGRAMS.

You would acknowledge the fact that these Diagrams would help a novice like me to grab the knowledge on SIP in more clarity using these Diagrams..

Hence request you to kindly accept my request and fix this issue.

Thanks in appreciation of your wonderful work and commitment.

Regards,

Hari.