It is, as far as I can see, permanently enabled. However, there does seem to be something in place to stop them being used as "free connections". Certainly, if I took mine away from here and tried to use it as a 4G connection, it would not work.
Potentially the BT hub is communicating via the 4G link confirming various details.
Haiving had two majopr outages, the 4G capability has been excellent.
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