I am a Note 5 user on Verizon Wireless. For the last 6 weeks or so, some of my text messages will be sent (appearing normally to me as they should), but will not show up on the other person's phone. This has been mostly happening with a friend who uses an iPhone on AT&T, so I assumed it wasn't a problem with my device. Yesterday, however, the exact same thing happened with my mother, who uses a Galaxy S5 on Verizon (both on a family plan).
After that, I switched from using Hangouts as my messaging app, to the default Verizon Messages+ app. The same thing happened with my iPhone-using friend this morning. Has anyone else experienced this? Is there something else I can do to troubleshoot it?