No network

[Becky1962]

I have not had a network for a week now so can not make any calls or send text messages. 
I can get services by  using wi-fi but some places can not use whattsapp that I need for work. 
I have tried everything in my phone. 
sky have left me 3 voice mails but. I can not get the messages as can not make any calls! 
It all started when Sky upgraded my phone last Monday evening. 
anyone else having the same problem.? 

[TimmyBGood]

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@Becky1962 wrote:

It all started when Sky upgraded my phone last Monday evening. 

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In what way?

[Becky1962]

I now have no network connection so can only use my phone when connected to wi-fi. Can not make any calls or text messages or receive any. 
I was upgraded to iOS 

[TimmyBGood]

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@Becky1962 wrote:

I was upgraded to iOS 

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Do you mean that the phone was replaced, or that the Apple operating system updated?