https://arstechnica.com/tech-policy/2019/01/verizon-price-hike-could-kill-free-texting-service-for-teachers-and-students/

A free texting service used by teachers, students, and parents may stop working on the Verizon Wireless network because of a dispute over texting fees that Verizon demanded from the company that operates the service. As a result, teachers that use the service have been expressing their displeasure with Verizon.

Remind—the company that offers the classroom communication service—criticized Verizon for charging the new fee. Remind said its service's text message notifications will stop working on the Verizon network on January 28 unless Verizon changes course. (Notifications sent via email or via Remind's mobile apps will continue to work.)