Any help with this would be appreciated?

Going from an iPhone which I was using iMessages to an Android. ATT seems to reset and go back to regular texts no problem. But on Verizon texts don't go through either way.

I have to have another Verizon iPhone user turn off their iMessages, we swap texts, then they can turn iMessages back on. Then texts start to flow between the two OS's just fine.

Why doesn't the network pick this up without having the iPhone user going through all that mess, and go back to regular texts like ATT's does?