said by ConstantineM:IPKall only provide incoming phone number termination, they don't even provide SIP registrations, you have to have a SIP registration with another provider. IPKall having a second place wouldn't make much difference at all; noone here is expecting for the COs to be in the cloud.
BTW, for what it is worth, there is actually no proof that IPKall is housed in a single place. It's my understanding that they have a presence at several COs; and as such, I would not be surprised if some of their numbers are serviced and terminated completely independent from others, meaning that should a single CO/DC go down, some other CO/DC would still continue to terminate at least some other numbers from other COs for at least half (etc) the customers.
Of course, it'd be interesting to know more about their actual setup.