Not natively. And it really has not much to do with ECE or anything, but about the Media Classes. If you're chatting, you're locked into that ECE_Chat MRD... you cannot change it to Cisco_Voice.
Now you could manipulate this. Let's say you're using Social Miners Agent API to conduct callbacks. You could call an API to enter the customers number, and their number would get queued for callback. Same logic would apply for the Outbound Dialer, although that would require a lot more work.
