#import <CoreTelephony/CTTelephonynetworkInfo.h>
#import <CoreTelephony/CTCarrier.h>

...
...

CTCarrier *provider [[[CTTelephonyNetworkInfo alloc] init] subscriberCellularProvider];
if(provider != nil) {
  NSString *providerName = [NSString stringWithString:[provider carrierName]];
  NSString *providerIsoCountryCode = [NSString stringWithString:[provider isoCountryCode]];
  //etc.
}

uses
   ..., iOSApi.Foundation, iOSApi.UIKit, iOSApi.CocoaTypes, iOSApi.CoreTelephony;
...
procedure TiOSTelephony.UpdateProviderInfo;
var
  networkInfo: CTTelephonyNetworkInfo;
  provider: CTCarrier;
begin
  try
    networkInfo := TCTTelephonyNetworkInfo.Wrap(TCTTelephonyNetworkInfo.OCClass.alloc);
    provider := networkInfo.subscriberCellularProvider;
    if Assigned(provider) then
    begin
      FProviderName := NSStringToString(provider.carrierName);
      FProviderISOCountryCode := NSStringToString(provider.isoCountryCode);
      FProviderMobileCountryCode := NSStringToString(provider.mobileCountryCode);
      FProviderMobileNetworkCode := NSStringToString(provider.mobileNetworkCode);
      FProviderAllowsVOIP := provider.allowsVOIP;
    end;
  except
  end;