Galaxy S4 missing calls but voicemail icon pops up

[Zacepi]

Hello all,

Have an old but perfectly functional S4 on O2.

I can call its number, it rings, then I leave a VM. The phone then sends a text saying a VM is waiting. So all peachy.

But - on occasion and it's happened several times, someone will call, the phone won't ring, and it won't send a text. However if I check then I can see the VM icon and call to check the VM.

I understand that the phone may have been out of signal hence the call routing to VM, but why in that case no text?

There isn't a pattern to this, and every time I test manually even with the phone out of signal it works perfectly - ie. when back in range I get a text reminder.

Any ideas?

[BandOfBrothers · Accepted solution]

This will be driven by the sim card @Zacepi

As a process of elimination does this happen if you try the sim card in another phone  ?

You may need to speak with customer service to check your account and or have your sim card replaced at an o2 store.

Sometimes extending the ringtime can help.

https://youtu.be/UqX9zBxURtE

[Zacepi]

Will get a new SIM, thanks