SIM card puzzle - please help

[Patrizio]

So I have this problem I can't work out. I have been using my O2 SIM card in my Samsung Galaxy A51 phone for about 3 years  without any issues at all. I am mostly at home but do go out every now and then. Then a few months ago, I wouldn't be able to make outbound calls and inbound calls would divert to voicemail. If I restarted the phone, I would be able to make and receive calls for a short while before the problem resumed.

I have changed my SIM card twice. The first time I changed the SIM card, it worked fine for a week or so before I started experiencing connectivity issues again. Again, restarting the phone resolves the problem temporarily.

So I then inserted my O2 SIM card in my housemate's Samsung Galaxy S8 device and it works like magic without any issues. I inserted my housemate's Vodafone SIM card into my phone, and that too works like a treat, easily able to make and receive calls. We have tested this for 5 days now, and no issues whatsoever.

This afternoon, I swapped my O2 SIM card back into my handset, the again the issues arose (calls not getting through sporadically). 

I had been hoping that by swapping SIM cards, I would be able to establish whether there was an issue with O2 signal in my house, or whether there was an issue with my phone. However, this test failed to identify the issue.

Has anyone else experienced this? Any thoughts as to why I might be getting this issue?

Thanks in advance.

[Enlli]

If this happens at home. Have you enabled WiFi Calling to see it that helps

https://www.o2.co.uk/connectivity/wifi-and-4g-calling

[Patrizio]

Thanks. Enabling Wifi calling at home does help, but it also means that when I do go out and have to rely on O2 signal, I can't make or receive calls.

[MI5]

@Patrizio 

At this stage I would get another O2 sim to try.

A free PAYG sim will do for testing purposes.

https://www.o2.co.uk/shop/sim-cards/pay-as-you-go

[Patrizio]

Hi, I have changed my O2 Sim card twice and the problem re-occurs. The issue is I have another 18 months left on my contract.

[pgn]

@Patrizio - the A51 has a dual SIM tray - does moving the SIM card into the other tray help at all?

[MI5]

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@Patrizio wrote:

Hi, I have changed my O2 Sim card twice and the problem re-occurs.

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I am aware of that.

The issue here is voltage related so you need to know if it is isolated to all O2 sim cards or just contract ones.

Ultimately, it is a phone fault so a check by Samsung would be a good idea.

[Patrizio]

Nope. Tried changing SIM card trays as well, but no difference

[madasaf1sh]

@Patrizio 

At this point I would speak to Samsung, and asking there advice, as what happens when you put a different o2 sim in your A51 , bear in mind it is out of warranty but Samsung may be able to offer advice.

[Cleoriff]

@Patrizio 

Samsung contact here

https://www.samsung.com/us/support/contact/ 

Or Call on

0333 000 0333