Not all of my text messages show in my messages history

[Fleischy99]

When checking my messages history not all of my messages are showing.  Why?  Is it something I did?  If I delete them from my mobile device does that remove them from my messaging history?

[FuzzyLogic]

Not sure which phone you have. These links may be of use:

How to find and retrieve deleted text messages on Android

Recover deleted messages in Messages on iPhone - Apple Support (CA)

[Syaoran]

There are certain scenarios where SMS/MMS messages are not picked up by the billing system.  When are you using WiFi Calling through a VPN (outside of Canada).  Also, when you are using apps like WhatsApp, Facebook Messenger, SnapChat, and many others to send messages.  RCS is hit and miss for messages being logged on your bill because it uses data and in some circumstances, messages are encrypted.