this is a big load on the servers, and will require extensive new hardware. My old blackberry 8520 had it , can't remember for the life of me what the service was called as it was a while ago, but when rogers started charging extra for it, I dumped it.
Now, I use Zoiper for Android and a voip.ms account. As soon as I get to a wifi zone (usually home or work) I forward my koodo# to my voip.ms #, and use the wifi to make and receive VOIP calls. Texting still handled through Koodo.