https://www.theverge.com/circuitbreaker/2017/9/16/16319676/essential-verizon-approval

Essential’s debut smartphone has received approval to run on Verizon, meaning it’s now supported by all four major US carriers. Sprint was the device’s launch partner, so it of course had support, and both AT&T and T-Mobile gave tacit support ahead of the phone’s launch.

But Verizon, for some reason, said it couldn’t guarantee that the Essential Phone would work and that the phone still had to clear a certification process. Evidently it’s now done that, with Essential tweeting out this morning that the phone is now compatible with Verizon.