I don't think the data shown is for 4 hours. It is for the period. Ask your Carrier for the period-wise data usage. You are not charged for the data consumption based on what is disaplayed on your iPhone.
What is the Last Reset Date* on your device? [Scroll all the way to the bottom]
Starting this Date* there are two sections which provide data for you analysis.
Under Cellular / Mobile Data Section
Current Period and Current Roaming Period cellular data usage.
[Scroll Down]
Call Time section
Current Period and Lifetime Calls.
How did you assess for which period the data usage belongs to?
Just to clarify, it's important to understand that a single SIM card can actually be used across multiple devices. This means that you can consume data from any device, including Android devices.
All the data consumption associated with that SIM card is consolidated in one central location: your trusted carrier. It's worth noting that your carrier will bill you based on this consolidated information. Therefore, if you need a comprehensive breakdown of your usage, I would recommend reaching out to your carrier and requesting a detailed itemized bill.
By doing so, you'll have a clear overview of your usage across all the devices you've used with that SIM card, ensuring transparency and accuracy in your billing.
If you're using an Exchange ActiveSync account, it may continue to use mobile data even if you've turned it off for Mail and Calendar. To see the mobile data usage of your Exchange ActiveSync account, go to Settings > Mobile Data > System Services.