Default [Q] Why can't I use my Verizon device with Ting?

Hi,

I currently have an unlocked, out-of-contract Verizon Galaxy Nexus, and I'm considering switching to Ting, a MVNO that uses Sprint's network. However, Ting says this isn't supported, and I was hoping someone here could help me understand why.

As I understand it, both Sprint and Verizon use CDMA, so I already have the hardware I need to communicate with Sprint's network. However, the ESN on my phone is not currently whitelisted on the Sprint network, therefore it won't work.

Ting has a bring your own device program. If your phone is on their whitelist, and it is Sprint branded, you can use it with their network. So I guess what I'm struggling to understand is why Sprint branded phones will work, but non-Sprint branded phones will not.

Is the fundamental issue simply here that Sprint refuses to whitelist my ESN because it is a Verizon phone? Or is there a technical reason why I can't use my Verizon Galaxy Nexus with Sprint? Is there anything I can do get my existing phone to work with Ting?

Thanks,
John