Best answer by Ed_Boost
There's the emergency non-disconnect period, which is the 24 hours period after you run out of credit. You won't go off supply during the 24 hours, giving you time to top up.
If you can't top up during these 24 hours, we also offer the 'emergency boost', which is up to £30 of discretionary credit to keep you going until you can next top up.
This option will only show when you've gone into that emergency period.
There's loads of info about the emergency boost feature on this topic: https://forum.boostpower.co.uk/smart-payg-23/check-this-out-emergency-boost-1011