[SR-Users] Kamailio Proxy and Asterisk

Hello, We have been using Asterisk for sometime and over the last year have started hosting instances for our clients on a vmware platform. These virtual pbx are located on public ip addresses and each customer has their own SIP trunk arrangements with various providers. We have decided to pool our resources and would like to start aggregating traffic. From reading online I have installed Kamailio 3.1.x with Asterisk 1.6.x. On top of this I have installed Siremis 3.2 in hopes of using it as a graphical front end. I am wanting to use Kamailio as a proxy to the SIP providers and allow the Asterisk to register only with Kamailio. Is there a link to some example configs with a tutorial pertaining to this type of deployment? If this is a good solution, it is my intention to recommend a consultant be hired to assist with a production server. I just need to learn allot more, before I can recommend Kamailio for the job. Do you think it's a good fit? Thank you for your kind responses, Greg