iMessage doesn't always come through on iPhone. What's the deal?

[ra4oasis]

For months, my wife gets most, but not all, iMessages on her iPhone 5s. But the missing messages always come through on her Mac and iPad though. When this happens, I can't tell which messages she gets, and which she doesn't. Any ideas as to what I should look at to fix it?

 

[vietalogy]

For months, my wife gets most, but not all, iMessages on her iPhone 5s. But the missing messages always come through on her Mac and iPad though. When this happens, I can't tell which messages she gets, and which she doesn't. Any ideas as to what I should look at to fix it?

It's a hit or miss with iMessage so I gave up on it long time ago and turned it off and just used whatsapp.

 

[Realistiic]

Could it be that some iMessages are going to the mobile number and some maybe going to a email address? it's probably the first thing I would check.