We need to host mutliple trixbox for more than one company i

We have a need to be able to host more than one trixbox on the same box. Would server virtualization be an option. I am running it as a VM using VMWARE server and it seems to be ok. We will only run sip so no need for special hardware.

I See that there are other vendor out there like lilyx who are offering this service? Does it work well.

The choppiness seems to be fixed if we rebuild the centos kernel with a vmware patch. Any suggestion on how to configure this box would be appreciated.

Is Xen a better option?