Mobile network connection dropping and reconnecting every second

[DaveEyes]

Just moved to Vodafone.  Put in sim and Switched on phone and all OK.

Once I make a call or receive a call the mobile network constantly drops and reconnects every second.

I then have to restart the phone to get a stable connection. 

If I put this sim in a different handset all is OK.

If I put a different sim in my handset all is OK.

Can anyone help me? 

Thanks 

Dave 

[AnnS]

It's a difficult one for sure @DaveEyes , for some reason the SIM may not be communicating with the phone, I wonder if a replacement SIM card may help.  If you would like to give a replacement SIM a try, you can order one here: SIM Swap As a workaround whilst this is being fixed you have data calling here: Data Calling 

You don't mention the phone you are using, I would also refer you to device guides here:  Device Guides 

If you are using a dual SIM phone, the main SIM would need to be in SIM slot 1, also take a look at eSIM if your phone support the service here: eSIM 

[DaveEyes]

Thanks for the reply.  I have replaced the sim and done a sim swap... But I get the same issue.

It's so bizarre... Another vodafone sim works OK in this phone (huawei p20 lite) and the sim I have works OK in a different phone.

I think the clue is that the problem only appears after a call has been made or received. Its got me stumped! 

[AnnS]

It certainly is confusing @DaveEyes , definitely not a SIM fault.

When you remove the SIM and place an alternative SIM in the phone, this refreshes the network, when the phone is rebooted, this does the same.  The same when you place the SIM in an alternative phone. 

I am beginning to think this may be due to the phone you are using.  Looking at the specification from GSMArena here: Huawei P20 lite the phone was released 2018.

To rule out a network issue please see the steps here: Network Issues 

[DaveEyes]

Thanks

Yes I think it's a setting on the phone..

I have tried a different huawei p20 lite and all works fine.

I have compared settings between the two p20 s but they look the same to me.

It's odd that it only does it after a call has been made or received. 

[AnnS]

Check you are connecting to the 4G network @DaveEyes 

Settings, connections  mobile networks network mode and make sure LTE is selected.

[DaveEyes]

Yes its definately 4G