You can use failover IPs for only on your attached OVH server.
Or same DCYou can use failover IPs for only on your attached OVH server.
You can not use them outside of the OVH network. But unlike the others answering in this thread, I will tell you the reason why:
OVH uses a VMAC system limiting their IPs to servers with that VMAC configured. Also the IPs are bound to a physical cable connected to a hypervisor/node/server which means that you can not transfer the IPs outside of OVH without OVH doing it for you.