I'm using the noname brand resellers, not the carriers themselves. I guess that's why.
I've tried a dozen thus far to no avail :c
I can hijack SMS routing entirely for inbound/outbound, but short of doing that I can't forge the from field and get the message delivered.
From what I've tested, T-Mobile and Verizon will both fail to deliver SMSes that aren't originated by the carrier listed in the SMS routing for a phone # (which is wholly separate from the PSTN routing of a number, and can be a source of problems when changing cell carriers).