Reddit user Geophyzze, who called up T-Mobile, said the company suspects it's a memory problem and advises subscribers to do a hard reset, clear out old text messages if that doesn't work, or to do a full factory restore if all else fails. To note, our editor's iPhone stopped going haywire after he disabled WiFi calling, so definitely try that first before doing a factory restore. We've reached out to both T-Mobile and Apple for answers and will update this post once we hear back.

Update: We're getting tips from readers on how they fixed the issue. Some had to disable Voice over LTE (VoLTE), while others had to completely switch off LTE in the meantime. Make sure to try those out before restoring your phones, which is no fun task, as you all know. [Thanks, Rob K and Behdad Sami!]

[Photo by Will Lipman]