question about BBM on BB10

following on from this post here about how data plans are handled on BB10, does anyone know if BBM is still sent via RIM servers in Canada?

Previously, this assured you that:
1. the communication was secure/encrypted (that's what got RIM in trouble in Dubai/UAE all those years ago)
2. not using any of your data allowance, even for sending pictures
3. FREE to use when roaming e.g. in a different country (because of point 2).

Does anyone know the hard answer here, in BB10? With maybe a source?

thanks