I don't think I've done anything to enable the caller ID. But I struggled with it for a while, until I found out that the CID is not guaranteed by voipms on their Value routing. It is a hit and miss - Rogers is not picking it up, and I'm not sure about Bell. Windmobile is receiving it and displaying the CID on calls from my voipms account. As soon as I've upgraded to the Premium service, my caller ID showed up on Rogers phones.
Since I didn't want to pay for the premium service I reverted back to Value, and got used to the fact that my caller ID is not always getting through and the call might not be answered...
hg