O2 Reception varies according to phone

[NickSheeran]

I have a conundrum with my personal iphone 12 which is on pay monthly O2. At home (and most other places) I only get one bar of network reception. However my wife's phone (also on O2 pay monthly) gets 4 bars. And my work mobile too (also O2 pay monthly) gets 4 bars. All three phones are in the same room; two getting 4 bars of reception but my personal phone only one bar. I thought it must be the fault of my iphone so I swapped the SIM from my work phone into my personal phone and Lo & Behold! my personal phone now gets 4 bars! So it cannot be the fault of my iphone. So it must be the SIM? But I have had three new SIMs from O2 over the past 4 weeks and none of them have sorted the issue. What can the resolution be?   

[pgn]

I was going to suggest removing and cleaning the SIM, then getting a replacement - but you have already done that.

As it is an iPhone, you may be able to get the phone checked over at an Apple store, if there is one with a repair team convenient to you?

Does your SIM perform similarly poorly when put into your work phone?

[japitts]

It can be perfectly normal for two phones on the same network to display different amount of coverage bars depending on the serving site they're connecting to, or also different carriers on the same site.

Unusual for the symptoms to be consistent, and for them to follow a SIM-swap. Does this cause any service issues? And do the bars vary if you're on a voice call?

[MI5]

@NickSheeran 

Are all phones showing 4g or 5g or a mix?

[pgn]

@NickSheeran - the 4G or 5G mentioned above could be a factor, if a mast issue exists in your area:

https://community.o2.co.uk/t5/Discussions-Feedback/o2-call-service-issue-affecting-many-customers-na...

This app running on both phones may help:

https://www.o2.co.uk/apps/my-network

Good luck.